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IB Biology HL > 1 cell biology > Flashcards

1 cell biology Flashcards

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1
Q

What is the function of the nucleus?

A

controls the metabolic activities of the cell as it contains genetic information in the form of DNA

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2
Q

What is the nucleolus?

A

area within the nucleus that is responsible for producing ribosomes

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3
Q

What is the function of mitochondria?

A

site of production of ATP in the final stages of cellular respiration

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4
Q

What are vesicles?

A

membranous sacs that are used to transport materials in the cell

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5
Q

What are lysosomes?

A

specialised forms of vesicles with hydrolytic enzymes that break down waste material in cells. they contain the enzyme lysozyme which breaks down the cell walls of certain bacteria.

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6
Q

What is the role of the cytoskeleton?

A

controls cell movement, movement of organelles within the cell, and provides mechanical strength to the cell

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7
Q

Name the three types of cytoskeletal filaments

A

microfilaments, microtubules, and intermediate fibres

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8
Q

Give two types of extension that protrude from some cells

A

flagella (whip-like protrusions) and cilia (tail-like protrusions)

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9
Q

What is the endoplasmic reticulum (ER)?

A

a network of membranes enclosing flattened sacs called cisternae

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10
Q

What are the functions of the two types of ER?

A

smooth ER – lipid and carbohydrate synthesis, and storage

rough ER – synthesis and transport of proteins

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11
Q

What is the function of the Golgi apparatus?

A

plays a part in modifying proteins and packaging them into vesicles

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12
Q

what is the smooth ER function

A

lipid and carbohydrate synthesis and storage

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13
Q

what is the rough ER function

A

protein synthesis and storage

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14
Q

What is the formula to calculate magnification?

A

magnification = size of image/actual size of object

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15
Q

why are cells stained before being viewed with a light microscope

A

staining increases contrast between different cell components, making them visible and allowing them to be identified.

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16
Q

what is an eyepiece graticule

A

a glass disc that fits on top of the eyepiece lens that is marked with a fine scale from 1 to 100

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17
Q

what is a stage micrometer

A

a microscope slide with a very accurate scale in micrometers engraved on it

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18
Q

what is a scientific drawing

A

a labelled line drawing that is used to highlight particular features and does not include unnecessary detail or shading, it should always have a title and state the magnification

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19
Q

what is magnification

A

how many times larger an image is than the actual size of the object being viewed

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20
Q

what is resolution

A

the ability to see indiviual objects as separate entities

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21
Q

what are living organisms composed of

A

cells (one or more)

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22
Q

what are the smallest units of life

A

cells, the basic unit capable of carrying out all the functions of a living organism

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23
Q

what do cells come from

A

pre-existing cells

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24
Q

what is the cell theory

A

living organisms are composed of cells
cells are the smallest unit of life
cells come from pre-existing cells

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25
Q

what is striated muscle tissue composed of

A

repeated units called sarcomeres

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26
Q

what do sarcomeres show under a microscope

A

a characteristic striped (striated) pattern.

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27
Q

what is distinctive about sarcomeres and their nuclei

A

it challenged the idea that cells have one nucleus, as the muscle cell (fibre) has more than one nucleus per cell. it’s multinucleated.

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28
Q

how long is straited muscle fibre cell

A

about 30mm

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29
Q

what is acetabularia

A

a genus of single celled green algae (gigantic)

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30
Q

how big is acetabularia

A

0.5 to 10 cm

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31
Q

what does acetabularia consist of

A

the rhizoid
the stalk
the cap

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32
Q

rhizoid of acetabularia

A

‘small roots’ at the bottom

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33
Q

the stalk of acetabualria

A

connects the rhizoid and cap

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34
Q

the cap of actabularia

A

a top umbrella made of branches that may fuse into a cap

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35
Q

what is attatched to the stalk of acetabularia

A

whorl of hairs that leave whorl scars

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36
Q

what notions does acetbaularia challenge

A

that they must be simple in structure and small in size

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37
Q

what are aseptate fungal hyphae

A

long threads (hyphae) with many nuclei

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38
Q

what are septa in septate fungal hyphae

A

dividing cell walls

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39
Q

what is the result of septate fungal hyphae

A

shared cytoplasm and multiple nuclei

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40
Q

what notions does aseptate fungal hyphae challenge

A

the idea that the cell is a single unit as the fungal hyphe have many nuclei, are very large and possess a continuous shared cytoplasm

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41
Q

how to convert from cm into mm

A

multiply by 10

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42
Q

how to convert from mm to micrometres

A

multiply by 1000

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43
Q

how to convert from micrometres to nanometres

A

multiply by 1000

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44
Q

unit for magnification

A

x the magnification

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45
Q

unit for size of drawing and actual size

A

whatever unit the question used or asked for

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46
Q

how to calculate magnification of an image using its scale bar

A

use a ruler to measure the length of the scale bar
convert this measurement to the same units as the scale bar
divide the image scale bar length by the actual image scale bar length

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47
Q

how to calculate the size of a specimen using its scale bar

A

measure the length of the specimen in mm
measure the length of the scale bar in mm
divide the length of specimen by length of scale bar
calcualte the size by multiplying the scale bar by the last answer. units same as scale bar

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48
Q

how to calcualte specimen size using magnification of an image

A

measure the length of the specimen in mm
convert the specimen length to micrometres
divide the length of the specimen by the magnification

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49
Q

metabolism is

A

the regular set of life supporting chemical reactions that takes place within the cells of living organisms

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50
Q

growth is

A

an increase in size or shape that occurs over a period of time

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51
Q

response is

A

a reaction (to a stimulus) by the living organism to changes in the external environment

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52
Q

homeostasis is

A

the maintenance of a constant internal environment by regulating internal cell conditions

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53
Q

nutrition is

A

the intake of nutrients, which may take different forms in different organisms. nutrition in plants involves making organic molecules (during photosynthesis) while nutrition in animals and fungi involve the absorption of organic matter

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54
Q

reproduction is

A

the production of offspring, either sexually or asexually, to pass on genetic information to the next generation

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55
Q

excretion is

A

the removal of waste products of metabolism and other unimportant materials from an organism

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56
Q

saprotrophs

A

excrete digestive enzymes onto food and absorb the nutrients

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57
Q

autotrophs

A

make their own food (like plants)

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58
Q

heterotrophs

A

must consumer other organisms

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59
Q

are viruses living

A

no they do not fulfill the functions of life

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60
Q

paramecium are

A

unicellular protozoa

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61
Q

what size are paramecium

A

0.25mm

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62
Q

where are pareamecium found

A

aquatic environemtns like stagnant ponds

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63
Q

how do paramecium move in all directions

A

using cilia

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64
Q

picture of a paramecium???

A

?

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65
Q

what are chlamydomonas

A

unicellualr green algae

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66
Q

what size is chlamyodomonas

A

10 to 30 micrometres

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67
Q

how do chlamyodomonas move

A

using flagella

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68
Q

chlamyodomonas diagram

A

????

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69
Q

which organisms have large SA:V

A

small organisms

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70
Q

which organisms have small SA:V

A

large organisms

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71
Q

as a cell grows, its volume increases by the power of

A

3 cubed

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72
Q

as a cell grows, its surface area increases by the power of

A

2 squared

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73
Q

if volume increases at 3 cubed and surface area increases at 2 squared, what happens to the SA:V

A

it decreases as the organism grows

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74
Q

what is ficks law

A

rate of diffusion = (concentration gradient + surface area) / distance

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75
Q

rate of diffusion =

A

(concentration gradient + surface area) / distance

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76
Q

why do large organisms have low metabolisms

A

they have small SA:V, and can hold onto heat and energy longer as they have less relative surface area

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77
Q

why do small organisms have high metabolisms

A

they have large SA:V and lose heat and energy very fast as they have more relative surface area

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78
Q

what part of a mammalian body is specialised to surface area

A

lungs, for oxygen

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79
Q

what is the genome

A

complete set of genes, chromosimes or genetic material present in a cell or organism, every cell except red blood cells

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80
Q

what is cellular differentiation

A

when an unspecialised stem cell changes and carries out a specific function in the body. cells differentiate to form different cell types due to the expression of different genes

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81
Q

according to WHAT, a complex system has properties that its constituent parts do not have. the whole is more than the sum of its parts

A

emergent properties

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82
Q

how many genes does the human genome have

A

21,000

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83
Q

totipotent

A

Can differentiate into any type of cell including placental cells.

Can give rise to a complete organism.

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84
Q

pluripotent

A

Can differentiate into all body cells, but cannot give rise to a whole organism.

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85
Q

multipotent

A

Can differentiate into a few closely related types of body cell.

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86
Q

unipotent

A

Can only differentiate into their associated cell type. For example, liver stem cells can only make liver cells.

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87
Q

when are totipotent stem cells found

A

basicallynone after birth

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88
Q

when are pluripotent stem cells found

A

very few in adults

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89
Q

what can multipotent stem cells do

A

become any cell in e.g. circulatory system

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90
Q

what can unipotnet stem cells do

A

become any cell in e.g. a heart

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91
Q

what is stargardts disease

A

an inherited from of juvenile macular degeneration, that causes progressive loss of centrl vision

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92
Q

when is stargardts disease

A

late childhood to early adulthood

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93
Q

what is stargardts disease caused by

A

a recessive genetic mutation in gene ABCA4, which causes an active transport protein on photoreceptor cells to malfunction. this ultimately causes photoreceptor cells to degenrate

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94
Q

how does stem cell therapy help stargardts disease

A

patients are given retinal cells derived from human embryonic stem cells which are injected into the retina. the inserted cells attach to the retina and become functional

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95
Q

stem cells in leukemia

A

harvesting hematopoietic stem cells (HSC’s) which are multipotent stem cells. they can be taken from bone marrow, perioheral blood or umbilical cord blood. the HSC may come from either the patient or from a suitable doner. the patient then undergoes chemotherapy and radiotherapy to get rid of the diseased white blood cells. the next step involves transplanting HSC’s back into bone marrow, where they differentiate to form new healthy white blood cells.

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96
Q

arguments for stem cells

A

cell therapy to eliminate serious diseases or disabilites
transplants can be easily obtained without requiring the death of another human or inflicting any kind of pressure on normal body which happens when someone donates an organ
the stem cells are harvested from the embryo at an early stage when the embryo has not yet developed a nervous system and thus it is not likely to feel any pain

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97
Q

how are embryo stem cell cultures harvested

A

removal of nucleus from donor egg cell
nuclear transfer of host dna from somatic cells
4 cell stage
morula
blastocyst
embryo stem cell culture containing transferred dna from host somatic cells

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98
Q

how are stem cells obtained from bone marrow

A

blood is taken and stem cells are seperated out

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99
Q

how are egg cells obtained

A

a woman takes fertility drugs and then an ultrasound guided needle is inserted.

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100
Q

why are adult stem cells less valued

A

because they have a narrower range of cells they can divide into

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101
Q

arguments for stem cell research (drug research)

A

more accurate than animals
GM foods
systemic toxication of drugs

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102
Q

arguments for stem cell research (developing science)

A

could be used in producing regenerated tissue for burns
replacement organs

(therapeutic)

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103
Q

what is stargardts macular dystrophy

A

a recessive mutation of ABCA4 which causes the retina cells to malfunction and photoreceptive cells to degenerate. this can lead to poor vision or severe loss of vision (blindness)

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104
Q

how are stem cells used in leukemia

A

stem cells are removed from bone marrow and frozen.
chemotherapy and radiotherapy is given to stop the body being able to make blood cells. then the stem cells are reinjected.

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105
Q

differences in eukaryotic and prokaryotic cells

A

Eukaryotic cells have a separate membrane-enclosed nucleus, whereas the DNA of prokaryotes is freely floating in the cytoplasm.

Eukaryotic cells have a complex system of membrane-bound organelles that divides the cell into numerous enclosed regions – known as compartmentalisation.

Prokaryotes do not have any membrane-bound organelles.

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106
Q

what do prokaryotes not have any of

A

membrane bound organelles

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107
Q

pili function

A

protein filaments on the cell wall that help in cell adhesion and in transferring of DNA between two cells

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108
Q

70S ribosomes

A

are the site of protein synthesis

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109
Q

plasmids

A

small circles of DNA that carry a few genes, often these give the cell antibiotic resistance and are used in creating genetically modified bacteria

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110
Q

difference in ribosome size between prokarytic and eukarytoic cells

A

ribosomes in prokaryotic cells (70S) are smaller than ribosomes found in eukaryotic cells (80S).

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111
Q

what do 70S and 80S refer to

A

sedimentation rate of RNA subunits

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112
Q

steps of binary fission in prokaryotes

A

The chromosome is replicated semi-conservatively, beginning at the point of origin (shown in red in Figure 2).
Beginning with the point of origin, the two copies of DNA move to opposite ends of the cell.
The cell elongates (grows longer).
The plasma membrane grows inward and pinches off to form two separate, genetically identical cells.

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113
Q

how are mitochondria insides sealed from the rest of the cell

A

mitochondrial envelope

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114
Q

advantages of eukaryotic cells being compartilised

A

Greater efficiency of metabolism as enzymes and substrates are enclosed, and therefore much more concentrated, in the particular organelles responsible for specific functions.

Internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes.

Isolation of toxic or damaging substances away from the cytoplasm, such as the storage of hydrolytic enzymes in lysosomes.

Flexibility of changing the numbers and position of organelles within the cell based on the cell’s requirements.

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115
Q

where is dna replicated

A

in the nucleus

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116
Q

how do you distinguish the golgi apparatus

A

it is not found near the nucleus
the lines are unattached to eachother
it has no ribosomes attatched

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117
Q

what is exocytosis

A

where things leave the cell through the plasma membrane

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118
Q

what is endocytosis

A

where things enter the cell through the cell membrane

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119
Q

what does the vacuole do

A

store liquid and sap which pushes the organelles against the plasma membrane. therefore the plasma membrane must be strong

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120
Q

what is transcription

A

copying the dna by synthesising messenger RNA (mRNA) from the DNA base sequences

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121
Q

what is translation

A

interpreting the genetic code to synthesise proteins (more specifically polypeptide chains) on ribosomes

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122
Q

microscope resolution def

A

the shortest distance between two seperate points in a microscopes field of view that can still be distinguished as distinct objects

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123
Q

do electron microscopes have a higher or lower resolution than light microscopes

A

much higher

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124
Q

what is the difference in resolution between an electron and light microscope

A

a light microscope is 200nm compared to 0.1nm

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125
Q

the ??? the value, the lower the resolution

A

higher

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126
Q

how many times can an electron microscope magnify objects by

A

500,000

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127
Q

how many times can a light mcirosocope magnify by

A

2000

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128
Q

compartmentalisation def

A

the formation of compartments within the cell by membrane bound organelles

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129
Q

which cells are compartmentalised

A

all eukaryotes where membranes are used to isolate certain parts of the cell from the rest to form separate organelles.

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130
Q

advantages of being compartmentalised

A
  • greater effiency of metabolism as enzymes and substrates are enclosed, and therefore more concentrated for their functions
  • internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes
  • isolation of toxic or damagin substances away from cytoplasm (like lysozyme)
  • flexibility of changing numbers and posisitions
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131
Q

how do prokaryotes reproduce

A

binary fission

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132
Q

how does binary fission work

A
  • chromosome replicated semi conservatively, beginning at point of origin
  • beginning there, the two copies of dna move to opposite ends of the cell
  • the cell elongates
  • the plasma membrane grows inward and pinches off to form two seperate genetically identical cells.
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133
Q

what causes the fluidity of the membrane

A

phopholipids, which have the ability to move with respect to each other in the same plane. cholesterol also helps

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134
Q

benefits of membrane fludiity

A

the cell can perfom processes such as endocytosis nad exocytosis

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135
Q

describe the fluid mosiac model,

A

phospholipid bilayers with proteins embedded in the bilayer, making the membrane look like a mosaic.

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136
Q

phosphate heads are hydro…

A

hydrophilic (love water)

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137
Q

what is a phospholiid

A

One type of lipid, called triglycerides, are made up of one glycerol and three fatty acid molecules.

a phospholipid is a lipid where one of the fatty acids has been replaced by a phosphate group

138
Q

fatty acids are hydro…

A

phobic

139
Q

what is an amphipathic molecule

A

A molecule that has both a hydrophilic and a hydrophobic part

140
Q

integral proteins are

A

amphipathic (they have hydrophobic and hydrophilic properties) and are embedded in the plasma membrane. In most cases, they pass completely through the membrane.

141
Q

peripheral proteins are

A

polar (hydrophilic) and are attached to the outside of the plasma membrane.

142
Q

channels in proteins

A

some proteins have a pore/channel that allows the passive transport (no energy required) of substances between the inside and outside of the cell.

143
Q

carriers in proteins

A

these proteins bind to substances on one side of the membrane and then change shape to transport them to the other side. Carrier proteins that use energy to change shape are termed protein pumps.

144
Q

recognition in proteins

A

certain proteins help the cell in differentiating between self and non-self cells (important in triggering an immune response).

145
Q

receptors in proteins

A

these proteins usually span the whole membrane to relay information from the inside or outside of the cell.

146
Q

enzymes in proteins

A

these are proteins that enhance the rate of reactions that happen at the membrane level.

147
Q

glycolipids are

A

a phospholipid and a carbohydrate attached together.

148
Q

cholesterol is

A

a sterioid and is found only in animal cell membranes.

149
Q

cholesterol is vital in

A

helping to maintain the structure of the cell membrane

150
Q

glcolipids are important in

A

maintaining the structure of the cell membrane and in cells differentiating between self and non-self cells.

151
Q

what to remember when drawing the fluid mosiac model

A

Individual phospholipid molecules are shown by using the symbol of a circle with two parallel lines attached.

A range of membrane proteins is shown, including peripheral and integral.

The following labels are included: phospholipid bilayer, phospholipid molecule, glycoprotein, glycolipid, integral and peripheral proteins and cholesterol.

152
Q

what is cholesterol

A

is a steroid made up of a non-polar part comprising four ring structures, a hydrocarbon tail, and a polar hydroxyl group

153
Q

cholesterol is amphipathic. this means it can

A

insert itself into cell membranes by interacting with the phospholipids (which are also amphipathic).

154
Q

choleserol in membranes restricts what

A

the movement of phopholipids and other molecules, reducing molecule fluidity.

also restricts membrane permeability to hydrophilic molecules and ions like sodium and hydrogen.

155
Q

what does cholesterol do at low temps

A

disrupts the regular packing of the hydrocarbon tails of phospholipid molecules, which prevents the solidification of the membrane. This enables the membrane to stay more fluid at lower temperatures, allowing the membrane to function properly.

156
Q

Davson-Danielli

A

MODEL

157
Q

what does simple diffusion require

A

a gas/liquid medium
concentration gradient from high to low
living and non-living organism

158
Q

what does faciliated diffusion require

A

specific channel or carrier proteins that vary depends on size or shape of entering molecule

159
Q

what does diffusion depend on or is effected by

A

temperature
surface area of membrane
size of particles
concentration gradient of diffusing particles

160
Q

what does active transport require

A

ATP

low to high concentraiton gradient

161
Q

endocytosis is

A

molecules in

162
Q

phagocytosis is

A

cell eating

163
Q

pinocytosis is

A

cell drinking

164
Q

what subsections of endoyctosis are there

A

phagocytosis

pinocytosis

165
Q

what is exocytosis

A

molecules out

166
Q

what is excretion of exoyctosis

A

undigested remains

167
Q

what is secretion of exocytosis

A

releasing enzymes from inside secretary vesicles attatched to inside plasma membrane wall

168
Q

give substnces to be transported

A

small non polar molecules
small ions
larger molecules
very large molecules

169
Q

example of small non polar molecules for transportation

A

oxygen or carbon dioxide

170
Q

example of small ions to be transported

A

Na+ or Ca2+ or K+

171
Q

example of larger molecules to be transported

A

glucose, nitrates

172
Q

example of very large molecules to be transported

A

proteins

173
Q

problems that may occur in transportation

A

very small molecules move super quick through p.b.
polar molecules cant get past the fatty acid tails of p.b.
larger molecules cant cross p.b. and sometimes have to go against conc grad
very large protein molecules cant cross membrane at all even using integral proteins.

174
Q

integral proteins

A

triangular soft lump

175
Q

transport proteins

A

like a chromosome

176
Q

periphal protein

A

oval lump on inside end of hydrophilic head

177
Q

channel protein

A

cylindrical shape going through p.b.

178
Q

what is a triglyceride

A

a glycrol and three fatty acids

179
Q

what is a phospholipid

A

a glycerol, two fatty acids and a phosphate gorup

180
Q

what does cholesterol control

A

membrane fluidity and permeability

181
Q

what is the ratio of total lipid surface area to total cell membrane surface area

A

2:1

182
Q

how did pasteur disprove the cell theory

A

Pasteur boiled nutrient broth in three swan-neck flasks. He then broke the neck of one flask to allow air to enter, but left the other flask unbroken. The broth in the flask where the swan neck was not broken remained clear (as no microbes were formed and any microbes from the air were trapped in the curve of the swan neck), while the broth in the broken-necked flask became cloudy, as microbes carried to the flask in the air grew and multiplied. In the third flask, Pasteur tilted the flask to expose the broth to the microbes in the curve of the swan neck. Pasteur’s experiment proved that spontaneous generation of cells and organisms does not occur on Earth, showing that the present conditions (temperature, pressure, light, radiation level and so on) do not sustain the process.

183
Q

what was the miller - urey experiment

A

Miller and Urey recreated the conditions of early Earth in a closed system by including a reducing atmosphere (low oxygen) with high radiation levels, high temperatures and electrical storms. After running the experiment for a week, some simple amino acids and complex oily hydrocarbons were found in the reaction mixture. This experiment proved that non-living synthesis of simple organic molecules was possible.

184
Q

whcih part of the cell theory did louis pasteur disprve

A

spontaneous generation

185
Q

which part of the cell theory did miler-urey disprove

A

that the first cell came from non living materiak

186
Q

what conditions are required for life to emerge and persist

A
  1. Simple organic molecules, such as amino acids, fatty acids and carbohydrates, must be formed.
  2. Larger organic molecules, such as phospholipids, RNA and DNA, must be assembled from simpler molecules.
  3. Organisms reproduce, so replication of nucleic acids must be possible.
  4. Biochemical reactions require set conditions, such as pH. Therefore, self-contained structures, such as membranes, are necessary.
187
Q

what does the endosymbiotic theory explain

A

the origin of eukaryotic cells

188
Q

what is the endosymbiotic theory

A

This theory supports the idea that mitochondria and chloroplasts were themselves prokaryotes that were taken in by larger prokaryotes by endocytosis.

Instead of being digested and broken down, these cells remained inside the host cells.

Cells that could carry out aerobic respiration and hence provide energy to their host cell (which were probably anaerobes who did not need oxygen) evolved into mitochondria.

Prokaryotic cells that could convert light energy to chemical energy (probably cyanobacteria) became chloroplasts and passed on sugars produced during photosynthesis to the host cell.

189
Q

what do both mitochondria and chloroplasts have

A

Have double membranes, as expected for cells taken in by endocytosis.

Have circular naked DNA, as in prokaryotes.

DNA is formed as single chromosomes.

Have 70S ribosomes, as in prokaryotes.

Divide by binary fission like prokaryotic cells.

Are susceptible to some antibiotics.

190
Q

what is mitosis used for

A

to produce new cells for growth and repair

191
Q

what is meiosis used for

A

the formation of gametes only

192
Q

how do bacteria reproduce

A

asexually by binary fission (NOT meiosis or mitosis)

193
Q

how do yeasts reproduce

A

asexually by budding (NOT meiosis or mitosis)

194
Q

interphase

A

period of cell growth
cell prepares cell for cell division (mitosis)
genetic material/dna is copied and checked for errors - prevents mutations being passed on
new organelles and proteins are made

195
Q

mitosis

A

process by which a nucelus divides into two - each with an identical set of chromosomes - the nuclei are genetically identical

196
Q

what are the four phases of mitosis

A 
prophase
metaphase
anaphase
telophase
(followed by cytokeneisis)
197
Q

what is cytokeneisis

A

division of the cells into two genetically identical daughter cells.

198
Q

G1 - the longest phase

A

protein synthesis - cell “grows”
most organelles produced
volume of cytoplasm increases
cell differentiation (switiching on or off genes)
if cell is not going to divide it stays in this phase

199
Q

S - replication phase

A

DNA replication - this must occur if mitosis is to take place. the cell enters this phase only if cell division is to follow.

200
Q

G2 - second growth phase, short

A

short gap before mitosis (cell division)
cytoskeleton of cell breaks down and the protein microtubule components begin to reassemble into spindle fibres - required for cell division

201
Q

when does mitosis occur

A

when an increase in number of cells is needed

202
Q

what are cancers caused by

A

uncontrolled cell division by mitosis

203
Q

what does a centromere do

A

hold 2 chromatids together

204
Q

what is a gene

A

a segment of DNA that codes for a trait

205
Q

chromatids are identical…

A

copies

206
Q

a chromosome is essentially made up of

A

2 sister chromatids

207
Q

how many pairs of chromosomes do we have

A

23 pairs, 46 chromosomes

208
Q

what does each pair of chromosomes contian

A

one chromosome from the father and one from the mother

209
Q

each indiviual pair of similar chromosomes is called

A

a homologous pair.

210
Q

where does mitosis take place?

A

replacement of cells (e.g. red blood cells, epidermal cells)
growth of tissues by producing new extra cells
divison of zygote into multicellular organism
formation of clones of T and B lymphocytes and plasma cells in the immune response
asexual reproduction
the production of genetically identical cells in multicellular organisms (allowing certain cells to retain the ability to develop into any other type if needed as a result of damage. )

211
Q

before a cell, it goes through interphase, where

A

its chromosomes are copied exactly, (replication), ATP is synthesised - provides energy for cell division; organelles are replicated and proteins are made.

212
Q

during prophase…

A

DNA of each chromosome is copied to form two chromatids (sister chromatids).
chromatids condense
nuclear envelope breaks down
chromosomes lie freely in the cytoplasm
centrioles move to opposite ends of the cell, forming protein spindle fibres which extend to the equator of the cell.

213
Q

during metaphase…

A

chromosomes line up at the equator, the spindle fibres from each pole become attached to the centromere of the chromosomes.

214
Q

during anaphase…

A

spindle fibres contract
centromeres are split and pairs of sister chromatids are seperated and dragged to opposite poles assuming a V shape, the centromeres lead.
a complete set of chromosomes is therefore found at each pole. ATP is required.

215
Q

during telophase…

A

chromatids reach their respective poles and uncoil - become thin and long and called chromosomes again.
spindle fibres break down
nuclear envelope forms around each group of chromosomes, forming two nuclei
cytokinesis follows, cytoplasm divides and a plasma membrane forms two indiviual cells; cell enters interphase once again.

216
Q

aside from pasteur, what other evidence is there that cells only come from pre-existing cells

A

a cell is a highly complex structure and no natural mechanism has been suggested for producing cells from simpler subunits
no example is known of increases in the number of cells in a population, organism or tissue without cell division occurring
viruses are produced from simpler subunits but they do not consist of cells, and they can only be produced inside the host cells that they have infected.

217
Q

what is mitosis

A

the division of the nucleus into two genetically identical daughter nuclei

218
Q

mitotic index =

A

total number of cells

219
Q

what is cytokinesis

A

the actual physical process of cell division

220
Q

cytokenesis in animal cells

A

the plasma membrane is pulled inwards around the equator of the cell to form a cleavage furrow.
this is done by a ring of contractile protein immediately inside the plasma membrane at the equator. the proteins are actin and myosin and are similar to the proteins that cause contrction in muscle. when the cleavage furrow reaches the centre, the cell is pinched apart into two daughter cells.

221
Q

cytokenesis in plant cells

A

the vesicles are moved to the equator where they fuse to from tubular structures across it.
with the fusion of more vesicles these tubular structures merge to form two layers of membrane across the whole of the equator, which develop into the plasma membranes of the daughter cells and are connected to the existing plasma membranes at the sides of the cell, completing division of the cytoplasm.

222
Q

what do cyclins do

A

ensure that everything is happening at the right time

223
Q

what do cyclins bind to

A

enzymes called cyclin dependent kinases.

224
Q

when cyclins have binded to the kinases what happens

A

thekinases become active and attach phosphate groups to other proteins in the cell. the attatchement of phosphate riggers the other proteins to become active and carry out tasks specific to one of the phases in the cell cycle.

225
Q

what are the four main types of cyclin in human cells

A

D
E
A
B

226
Q

what does cyclin D do

A

triggers cells to move from G0 to G1 and from G1 to S

227
Q

what does cyclin E do

A

prepares the cell for DNA replication in the S phase

228
Q

what does cyclin A do

A

activate DNA replication inside the nucleus in the S phase

229
Q

what does cyclin B do

A

promote the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis.

230
Q

what is a mutation

A

a change in an organism’s genetic code. a change in the base sequence of a certain gene can result in tumour formation. however, some parts of a gene do not code for anything so a mutation in these areas will not affect the organism. so not all gene mutations lead to uncontrolled cell division.

231
Q

what are mutagens

A

the agents that cause gene mutations. although not all mutations result in cancers, anything that causes a mutation has the potential to cause a cancer.

232
Q

what can mutagens be

A

chemicals referred to as carcinogens, such as asbestos or dioxin.
high energy radiation like x rays
short wave UV light
viruses like hepatitis B

233
Q

what are oncogenes

A

a mutated gene that contributes to the development of a tumour. in their normal, un-mutated state, oncogenes are called proto-oncogenes, and they help in the regulation of cell division

234
Q

once abnormal cell division has started at a particular place in the body,

A

a malignant primary tumour begins to form. if left untreated, this may follow a particualr development pathway to form secondary tumours.

235
Q

what is metastatis

A

when a primary tumours follow a particular development pathway to form secondary tumours.

236
Q

metastatis steps

A

cancerous cells detatch from the primary tumour
some cancerous cells gain the ability to penetrate the walls of lymph or blood vessels and so circulate around the body.
the circulatin cancerous cells invade tissues at different locations and develop, by uncontrolled cell division, into secondary tumours.

237
Q

metastasis definition

A

movement of cells from a primary tumour to other parts of the body where they develop into secondary tumours.

238
Q

in which place in the cell cycle do mutations happen

A

S-synthesis

239
Q

inwhich place in the cell cycle do genes become modified to an oncogene

A

G2 primaryily

240
Q

what are cyclins

A

a group of proteins whose function is to regualte the progression of a cell through the cell cycle.

241
Q

what do two strands of RNA form

A

DNA

242
Q

what to nucleotides join together ot form

A

a single stranded nucleic acid (RNA)

243
Q

each nucleotide is made up of how many parts

A

3

244
Q

what are nucleotides made up of

A

carbon, hydrogen , oxygen, nitrogen and phosphorus.

245
Q

when is a phospholipid formed

A

when a phosphate group replaces one of the fatty acids. these are vital to forming cell membranes

246
Q

what affects the physical proprties of the tri-glyceride

A

the length, and whether the fatty acids have double or single carbon bonds

247
Q

what is a triglyceride

A

3 fatty acids and 1 glycerol

248
Q

what is a fatty acid

A

a chain of carbons and hydrogens with a carboxylic acid group. the length of the chain can vary from 4 - 28 carbons

249
Q

what is simple diffusion

A

passive movement of molecules/ions along a conc grad

250
Q

what is facilitated diffusion

A

facilitated diffusion is passive movement of molecules/ions along a conc grad through a protein channel without use of energy

251
Q

what is osmosis

A

net movement of water across a partially permeable membrane from a region of high conc to low conc

252
Q

what is active transport

A

the movement of molecules/ions against the conc grad with the use of ATP

253
Q

what is endocytoisis

A

the infolding of the membrane/formation of vesicles to bring molecules into the cell with use of energy

254
Q

what is exocytosis

A

the infolding of the membrane of vesicles to bring molecules from the cell with use of energy

255
Q

what does cytokinesis involve

A

It involves the formation of a cell plate in plant cells only.

256
Q

Cholesterol has a role in making sure which type of protein is anchored to the membrane?

A

peripheral

257
Q

what does “The oldest fossilised cells resemble prokaryotes.” suggest

A

the idea that prokaryotes evolved before eukaryotes

258
Q

State the name of the molecule that CDKs attach to proteins in order to activate them.

A

phosphate group, prompting proteins to carry out their specific fucntion

259
Q

example of a therapuritc use of a stem cell

A

restoration of myocardial tissue

260
Q

how large are bacterium

A

around 1 micrometer

261
Q

how large are plant and animal cells

A

around 100 micrometers

262
Q

how large are viruses

A

100nm

263
Q

when does cytokenesis occur

A

after nuclear division in mitosis

264
Q

what do prokaryotes not have

A

golgi apparatuses or nuclear membranes

265
Q

The smooth endoplasmic reticulum is responsible for the synthesis and storage of

A

lipids

and steroids

266
Q

Cholesterol is made up of a nonpolar part composed of four ring structures, a hydrocarbon tail and which of the following groups?

A

polar hydroxyl group

267
Q

Recognition proteins are able to differentiate between substances. This is useful and helps them to trigger which type of response?

A

immune

268
Q

Which cell structure, important in endocytosis and exocytosis, promotes the movement of materials within a cell? (Answer with one word)

A

vesicles

cytoskeleton

269
Q

how are cyclins activated

A

by the phosphorylation by a CDK-activating kinase (CAK).

270
Q

what does cholersterol do within the plasma membrane

A

reduce membrane fluidity at high temps

271
Q

why is it beneficial that cholesterol is amphipathic

A

its attracted to both polar and non polar molecules, so can interact with polar phosphate heads and the non polar fatty acid tails. buffer of membrane fluidity, so that the fluidity is always at a good level for the cells

272
Q

at low temps, the phospholipids in the membrane do not have enough energy to move around…

A

vigorously, so clump together, meaning that the membrane fludiity is too low. cholesterol can interact with the fatty acid tails, dispersing them so that they can’t clump together. This increases the membrane fluidity

273
Q

At high temperatures, the phospholipids in the membrane have too much energy and move around too much which…

A

increases the fluidity of the membrane to the point where it becomes leaky. This is bad as the role of the membrane is to control very tightly what substances can enter and exit the cell. In this scenario, cholesterol interacts with the phosphate heads, pulling them together so that they don’t move around as much as the fluidity is reduced to a good level.

274
Q

A cell that is dividing too rapidly may have lost its ability to enter which part of the cell cycle

A

G1

275
Q

what were pasteur’s swan necked flasks filled with

A

nutrient broth and then sealed. some flasks were boiled to kill living organisms inside them. no microorganisms developed. spon. gen. rejected

276
Q

do ribsomes have membranes

A

no

277
Q

The Miller-Urey experiment was able to produce some simple organic molecules. Complex oily hydrocarbons were synthesised, as well as which other type of simple compound?

A

amino acids

278
Q

DNA is loosely packaged by histones to form which molecule? (Give your answer with one word)

A

chromatin/nucleosomes

279
Q

which cyclin triggers the start of mitsois

A

cyclin b

280
Q

Biologists suspect that endosymbiosis gave rise to mitochondria before chloroplasts because:

A

All eukaryotes have mitochondria, whereas many eukaryotes do not have chloroplasts.

281
Q

Some membrane-spanning proteins are able to change shape to allow materials to cross the cell membrane. Name the type of integral membrane protein that has this function.

A

protein pump

282
Q

The Miller-Urey experiment attempted to recreate the early atmosphere of a younger Earth. Which of the following best describes the early atmospheric conditions?

A

low oxygen atmosphere
high radiation levels
high temperatures
electrical storms

283
Q

how thick is a plasma membrane

A

10 nm

284
Q

function of prokaryotic cell walls

A

prevent cell bursting in hypotonic solutions.

maintain cell shape under various conditions.

285
Q

factors contributing to the development of malignant tumours

A

mutagens such as short-wave UV, mutations in oncogenes and ability to form secondary tumours

286
Q

is infrared light a mutagen

A

no

287
Q

somatic cell nuclear transfre

A

AEBE

adult somatic cells
enucleated egg ccell
blastula
embryonic stem cells

288
Q

nuclear reprogramming

A

RAI

reprogramming factors
adult somatic cells
induced pluripotenti cells

289
Q

evidence for davson danelli model

A

phospholipids
sa was twice sa of a red blood cell

proteins
protein coat to explain the differential permeability of the plasma membrane
implied fixed positions

electron mirographs
plasma appeared as two dark bands on the outside with alight band in between

290
Q

what falsified the davson danelli model

A

freeze fracture electron micrographs
showed globular proteins present don’t eh upper surface of the inner phospholipid layer

proteins had hydrophobic parts nad varied in size. suggested they were embedded within the bilayer and hydrogphoic regions could attract the fatty acid tails

x ray diffraction
at higher temps the membrane behaved as a liquid

membrane proteins of two cells linked to two florescent labels.
two cells fused. after a short time they were fully mixed. proved that tprotiens were free to move within the membrane

291
Q

tranpsort proteins

A

channels to allow susbtanes to passively move through the membrane
pumps for active transport

292
Q

glycoproteins

A

cell to cell communication
recet=ptors for chemical signals such as hormones.
cell to cell recognition
antigens
cell adhesion
binding cells together

293
Q

is chcholesterol amphipathic

A

yes

294
Q

what is the phospholipid bilayer permeable to

A

water
co2
o2
fatty acids
urea

295
Q

what is the phospholipid bilayer impermeable to

A

amino acids
glucose
hydrogen ions
chloride ions

296
Q

hat are channel protein specific for

A

a single substance

297
Q

What is the main role of ATP in the action of a Sodium-Potassium pump?

A

donates a phosphate to the grouo

298
Q

Lysosomes are often absent from plant cells and so a different organelle will take on the role of the lysosome. State the name of the plant cell organelle that is capable of doing this role.

A

vacuole

299
Q

what controls shape change in sodium potassium pumps

A

ion conentration, phosphate release

300
Q

State the name of the molecule that CDKs attach to proteins in order to activate them.

A

phopshates

301
Q

state the name of the eukaryotic organelle that helps to establish microtubules during cell division

A

centrioles

302
Q

state the name of the eukaryotic organelle that helps to establish microtubules during cell division

A

centrioles

303
Q

Biologists suspect that endosymbiosis gave rise to mitochondria before chloroplasts because:

A

all eukaryotes have mitochndria whereas many eukaryotes dont have chloroplasts

304
Q

In a cell, the following reaction takes place: glucose → ethanol + carbon dioxide. The reaction yields a small amount of ATP. This reaction can take place in:

I: A yeast cell
II: A plant cell
III: A human cell

A

I and II

305
Q

how does active transport across sodium potassium pumps be summarised

A

When the pump is open to the inside of the axon, three sodium ions (Na+) enter the pump and attach to their binding sites.
ATP donates a phosphate group to the pump.
The previous stage causes the protein to change shape expelling Na+ to the outside.
Two potassium ions (K+) from outside then enter and attach to their binding sites.
The binding of the K+ leads to the release of the phosphate which causes the pump to change shape again so that it is only open to the inside of the axon.
K+ is released inside.
Na+ can now enter and bind to the pump again.

306
Q

purpose of pcr

A

amplify small fragments of dna

307
Q

PCR

A

Denaturation – DNA sample is heated (~90ºC) to separate the two strands
Annealing – Sample is cooled (~55ºC) to allow primers to anneal (primers designate sequence to be copied)
Elongation – Sample is heated to the optimal temperature for a heat-tolerant polymerase (Taq) to function (~75ºC)

308
Q

what does taq polymearse actually do

A

extend the nucleotide chain from the primers - therefore primers are used to select the sequence to be copied.

309
Q

purpose of gel electrophoresis

A

used to separate and isolate proteins or dna fragments based on mass/size

310
Q

how is dna cut in half

A

by restriction endonuclease

311
Q

why do fragments seperate in dna seperation

A

because dna is negatively charged due to the presence of a phosphate group on each nucleotide.

312
Q

protein seperation in gel elctrophoresis

A

Proteins may be folded into a variety of shapes (affecting size) and have positive and negative regions (no clear charge)
Proteins must first be treated with an anionic detergent (SDS) in order to linearise and impart a uniform negative charge
Protein samples are placed into a polyacrylamide gel and sizes compared against known industry standards
Separated proteins are transferred to a membrane and then target proteins are identified by staining with specific monoclonal antibodies (Western blotting)

313
Q

gene modification by gene transfer:

A

isolate the desired gene from the original species using restriction endonucleases

isolate an appropriate plasmid (small loop of DNA containing a few genes that is often traded between bacteria)

Cut the plasmid with the same restriction endonuclease that was used to remove the desired gene. This will open the loop of the plasmid, forming a string with two ends.

Mix many copies of the target gene and cut plasmid together to allow their complementary unpaired sequences to join together, thus adding the gene into the plasmid.

Use the enzyme DNA ligase to covalently bond the DNA backbones of the gene and plasmid together, permanently sealing the gene into the plasmid loop.

Transfer the plasmid with the target DNA (called a recombinant plasmid) back into the bacterium.
Grow colonies of the genetically modified bacteria that now produce a eukaryotic protein.

314
Q

what is different with gene transfer of eukaryotic cells

A

If the gene is eukaryotic, use reverse transcriptase to produce an edited version of the gene. Although the genetic code is universal, eukaryotes delete parts of the RNA before it leaves the nucleus to be translated. Bacteria have no nucleus and cannot perform this step, so scientists compensate by making DNA without the parts that should be deleted.

315
Q

what are the consequences of sticky ends

A

Most restriction endonucleases leave ‘sticky ends’ where one half of the helix extends beyond the other, leaving a few unpaired bases. Using the same restriction endonuclease gives the gene and the plasmid complementary unpaired sequences that ‘stick’ together by hydrogen bonding.

Alternatively, use a restriction endonuclease that produces blunt ends for both gene and plasmid. Then add a series of guanine nucleotides to the 5’ ends of the gene, and cytosine nucleotides to the 5’ ends of the plasmid. This creates complementary sequences that will allow them to stick together.

316
Q

what is cdna

A

complementary dna

317
Q

plants methods of cloning

A

runners
bulbs
tubers

318
Q

fungus method of cloning

A

budding

319
Q

animals method of cloning

A

budding
parthenogenesis

320
Q

scientific methods of cloning

A

Splitting or fragmentation of an embryo to clone an animal before the cells have differentiated.

Using differentiated cells and somatic cell nuclear transfer to clone adult animals.

321
Q

Using differentiated cells and somatic cell nuclear transfer to clone adult animals.

A

Donor somatic (body) cells are taken from the organism that will be cloned and cultured in the lab.
Somatic cells with the least DNA inactivation should be chosen. In this case, cells were taken from the udder of the donor sheep.
The cell is starved so that the amount of cellular material other than the nucleus is reduced.
An unfertilised egg is taken from another individual.
The unfertilised egg is enucleated (the nucleus is removed).
In this case, the nucleus was removed using a tiny pipette.
The enucleated egg is fused with a donor cell.
In this case, the cells were placed next to each other and an electrical current was used to disrupt the cell membranes enough so that they would fuse together.
The fused cell is allowed to divide until a small embryo has formed.
The embryo is transplanted into the uterus of a surrogate mother.
The pregnancy and birth of the offspring proceed normally.

322
Q

what is methane

A

is a carbon molecule which is produced in anoxic conditions and can oxidise into carbon dioxide and water.

323
Q

methanogenic archeans

A

bacteria that are found in several anoxic environments and produce methane as part of the carbon cycle.

324
Q

ruminants

A

mammals that have a mutualistic relationship with methanogenic archaeans that help them to digest cellulose from the cell walls in the plants they eat. This creates methane, which is released as gas from the mammal.

325
Q

graph representing the change in cell sa to vol ration with increaseing cell diameter

A

curve with point close to x

326
Q

as size increases

A

sa:vol decreases

327
Q

what do phagocytic and whit eblood cells and photosyntheitcic baterium have

A

70s ribsomes

328
Q

is evaporation of water from sweat on the skin surface osmosis

A

no

329
Q

two sugar monomers make

A

a disaccharide

330
Q

waht makes up a digyceride

A

a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages.

331
Q

spec heat cpaacity of methane

A

2.2

332
Q

latent heat of vap of methane

A

760

333
Q

bp of methane

A

-160

334
Q

what is common to rna and dna

A

nitrogenous bases

335
Q

which organisms produce methane in anaerobic environments such as waterlogged soils

A

archea

336
Q

HIv leads to

A

a reduction in the production of antibodies

337
Q

what is produced by type II pneumocytes

A

pilmonary surfactant

338
Q

how do neonictinoid pesiticdes caues paralysis and death of honeybees

A

bind to neurotransmitter receptors

339
Q

what contribution did the x ray diffraction conducted by rosaling franklin make to our understanding of dna

A

indicated the helical shape of themolecuel

340
Q

all flowering plants depend on the …

A

duration fo periods of light and darkness to regualte the timing of reproduction

341
Q

effect of disruptive selection

A

favours indiviuals with intermediate forms of a characteristiic

342
Q

waht do the intercostal muscles do during exhalaation

A

external intercostal muscles contract and internal intercostal muscles relax

IB Biology HL (15 decks)

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