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BIOLOGY > 2A-Cell structure and division > Flashcards

2A-Cell structure and division Flashcards

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1
Q

What is a eukaryotic cell

A

Eukaryotic cells are complex and include all animal and plant cells as well as cells in algae and fungi

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2
Q

What is a prokaryotic cell

A

Prokaryotic cells are smaller and simpler like bacteria

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3
Q

What and where is plasmodesmata

A

It is channels for exchanging substances with adjacent cells in the cellulose cell wall

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4
Q

Describe algae cells

A

Similar to plant cells they have all the same organelles including cell wall and chloroplast

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5
Q

What are the two key differences between a fungal cell and a plant cell

A

In fungal cells the cell wall is made up of chitin not Cellulose
They also don’t have chloroplasts as they do not photosynthesise

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6
Q

What is the cell-surface plasma membranes description

A

Description – found on surface of animal cells, made up of mainly lipids and protein

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7
Q

What is the function of the cell surface plasma membrane

A

1-Regulates movement of substances in and out of cell

2-Has receptor molecules on it which allows it to respond to chemicals like hormones

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8
Q

Description of nucleus

A

Large organelles surrounded by nuclear envelope (double membrane )which contains many pores
Contains chromosomes made from protein-bound linear DNA
Contains nucleolus

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9
Q

Function of the nucleus

A

Control cells activities
DNA contains instructions for making proteins
pores allow substances e.g. RNA to move between the nucleus and the cytoplasm
nucleolus makes ribosomes

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10
Q

Description of mitochondrion

A

Oval shaped
double membrane-The inner one is folded to form structure called Cristae
inside is the matrix which contains enzymes involved in respiration

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11
Q

Function of mitochondrion

A

Aerobic respiration, where ATP is produced

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12
Q

Description of chloroplast

A

Small flat structure in plant and algal cells
surrounded by double membrane also has membranes inside called thylakoids membranes- these membranes are stacked in some parts of chloroplasts to form Grana
Grana linked together by lamellae

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13
Q

Function of chloroplast

A

Where photosynthesis takes place

parts photosynthesis happen in grana and other parts in stroma

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14
Q

description of Golgi apparatus

A

group of fluid filled membrane bound flattened sacs

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15
Q

function of Golgi apparatus

A

processes and packages new lipids and proteins

makes lysosomes

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16
Q

description of Golgi vesicle

A

small fluid filled sac in cytoplasm surrounded by membrane produced by Golgi apparatus

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17
Q

function of Golgi vesicle

A

stores lipids and proteins made by Golgi apparatus and transports them out of cells

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18
Q

description of lysosome

A

round organelle surrounded with membrane

type of Golgi vesicle

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19
Q

function of lysosomes

A

digestive enzymes called lysozymes contained which are kept separate from cytoplasm by membrane and used to digest invading cell,s or to break down worn out parts of cell

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20
Q

description of ribosome

A

very small
either floats in cytoplasm or attached to th rough endoplasmic reticulum
made proteins and rna

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21
Q

function of ribosomes

A

where proteins are made

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22
Q

description of rough endoplasmic reticulum

A

system of membrane enclosing a fluid filled space

covered with ribosomes

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23
Q

function of RER

A

folds and processes proteins which have been made at ribosomes

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24
Q

description of smooth endoplasmic reticulum SER

A

same as red but no ribosomes

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25
Q

function of SER

A

synthesises and processes lipids

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26
Q

description of cell wall

A

rigid structure
in plant and algae its made of carbohydrate- cellulose
in fungi its made up of chitin

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27
Q

function of cell wall

A

supports cell and prevents change in shape

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28
Q

description of cell vacuole

A

membrane bound
found in cytoplasm
contains cell sap-weak solution of sugar and salts
surrounding membrane called the tonoplast

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29
Q

function of cell vacuole

A

maintains pressure inside cell to keep it rigid
stops wilting
involved in the isolation of unwanted chemicals inside the cell

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30
Q

how are epithelial cells specialised

A

To absorb food efficiently in the small intestine
walls of small IN have villi (finger like projections)-increases surface area
Epithelial cells have microvilli(folds in cell membrane)-increase surface A even more
also has lots of mitochondria to increase energy for respiration

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31
Q

Explain cytoplasm of a prokaryotic cell

A

It has no membrane-bound organelles

It has ribosomes but they’re smaller than those in a eukaryotic cell

32
Q

Explain the plasma membrane in prokaryotic cell

A

Same as in eukaryotic cell made of lipids and proteins controls movement in and out of cells

33
Q

Explain flagellum in prokaryotic cell

A

Long hair like structure the rotates to make the cell move

not all prokaryotes have a flagellum

34
Q

Explain how prokaryotes don’t have a nucleus

A

Instead they have DNA which floats free in cytoplasm

its circular DNA presents as one long coiled up strand it’s not attached to any histone proteins

35
Q

Explain plasmids in prokaryotes

A

Plasmids are small loops of DNA

they contain genes for things like antibiotic resistance and can be passed between prokaryotes

36
Q

Explain cell wall in prokaryotic cells

A

Supports the cell and prevents it from changing shape it’s made of polymer called murein
murein is glycoprotein

37
Q

What is a glycoprotein

A

A protein with a carbohydrate attached

38
Q

Explain prokaryotes with capsule

A

Prokaryotes like bacteria have capsule made ups of secreted slime
it helps protect bacteria from attacking cells

39
Q

What are viruses

A

Acellular

40
Q

Describe a virus

A

Nucleic acid surrounded by protein smaller than bacteria

41
Q

How is a virus different to a bacterial cell

A

It has no cytoplasm no cell membrane and no ribosomes

42
Q

Describe structure of virus

A

Contain core of genetic material either DNA or RNA protein coat around core is the capsid attachment protein stick out from edge of capsid these let viruses cling onto host cells

43
Q

How does prokaryotic cells replicates

A

By binary fission

44
Q

Explain steps of binary fission

A

One – circular DNA and plasmids replicate
2-cell gets bigger and DNA loops move to opposite poles of cell
3-cytoplasm divides, new cell wall begins forming
4-cytoplasm divides and two daughter cells are produced
each daughter cell has one copy of circular DNA but can have variable number of copies of plasmids

45
Q

How do viruses use host cells to replicate themselves

A

1 – viruses use attachment proteins to bind to complimentary receptor proteins on surface of Host cell
2-as viruses are a cellular viruses, can’t undergo cell division instead they inject their DNA or RNA into host cell and then host cell replicates the viral particles

46
Q

Magnification formula

A

Size of image/size of real object

47
Q

Define resolution

A

How well a microscope distinguishes between two points that are close together

48
Q

Describe optical microscopes

A

1– use light form image
2– maximum resolution of 0.2 micro metres
3– maximum useful magnification times 1500

49
Q

Describe electron microscopes

A

1 – use electrons to form image
2 – have higher resolution than optical microscopes
3– maximum resolution of 0. 0002 micro metres
4 – the maximum useful magnification is 1,500,000

50
Q

Two types of electron microscopes

A

Transmission electron microscope or scanning electron microscope

51
Q

Describe TEM

A

1-Use electromagnets to focus beam of electrons which then transmits through the specimen
2 – denser part of specimen absorb more electrons which makes them look darker
3 – advantage they give high resolution images so you see internal structure of organelles like chloroplast
4 – can only be used on thin specimens

52
Q

Describe SEM

A

1 – scan beam of electrons across specimen this knocks off electron from the specimen these are gathered in cathode ray tube to form image
2 – image shows the surface of specimen, can be 3D
3– advantage can be used on thick specimens
4– but they give lower resolution image than TEM

53
Q

PRACTICAL how to view specimens on the optical microscope using slide

A

Pipette small drop of water onto slide, use tweezer place a section of specimen on water, add drop of stain, finally add coverslip

54
Q

what stains show what

A

IODINE-starch

EOSIN-cytoplasm

55
Q

What are the three stages of cell fractionation

A

1 – homogenisation
2-filtration
3-ultracentrifugation

56
Q

CELL FRACTIONATION- explain homogenisation

A

1-grind cells up in blender, breaking up plasma membrane releasing organelles into solution
2-solution must be ice cold to reduce enzyme activity which breaks down organelles
3-solution must be isotonic(same concentration of chemicals as cell being broken dow to prevent damage of organelles through osmosis)
4-buffer solution added to maintain PH

57
Q

CELL FRACTIONATING- explain filtration

A

Filtered through goes to separate large debris or tissue debris

58
Q

CELL FRACTONATION- ultracentrifugation

A

1-cell fragments poured to tube, put in centrifuge, spun at low speed, heaviest organelles(nuclei)go to bottom(pellet), rest of organelles stay suspended at top (supernatant)
2-supernatant drained and added to another tube to repeat process at higher speed this time the pellet is mitochondria

59
Q

What are the three phases of interphase

A

S-synthesis cell replicates DNA
G2-Cell keeps growing and proteins needed for cell division are made
M- mitosis
G1-cell grows and new organelles and proteins are made

60
Q

Explain interphase

A

cell carries out normal functions, DNA unravelled and replicated, organelles replicated, ATP increased so it has enough energy

61
Q

four stages of Mitosis

A

1- Prophase
2-Metaphase
3-Anaphase
4-Telophase

62
Q

MITOSIS- explain prophase

A

Chromosomes condense getting shorter and fatter, central start moving to opposite ends of cells forming protein fibres called spindle, nuclear envelope breaks down, chromosomes lie free in cytoplasm

63
Q

MITOSIS- explain metaphase

A

Chromosomes each with two chromatids line up along middle of cell becoming attached to the spindle by their centromere

64
Q

MITOSIS- explain Anaphase

A

CentROMERES divide separating each pair of chromatids ,spindles contract pulling chromatids to opposite poles ,this makes chromatids appear V shaped

65
Q

MITOSIS- explain Telophase

A

Chromatids reach opposite poles on spindle, they uncoil and become long and thin, now chromosomes again, nuclear envelope forms around each group of chromosomes so there are two nuclei, the cytoplasm divides (cytokinesis) – now two daughter cells that are genetically identical to original cell

66
Q

Explain how cancer is the result of uncontrolled cell division

A

Mitosis and cell cycle are controlled by genes, if there is a mutation in a gene that control cell division the cells grow out of control, cells keep dividing which form a tumour, cancer is a tumour that invades surrounding tissue

67
Q

Explain cancer treatment which targets G1

A

Chemotherapy prevents the synthesis of enzymes needed for DNA replication when these are produced cell is unable to enter synthesis phase forcing cell to kill itself

68
Q

Explain cancer treatment which targets the S phase

A

Radiation and some drugs damage to DNA at several points in cell cycle DNA is checked for damage if damage is detected the cell will kill its self

69
Q

How to prepare optical slide

A 
1- clip prepared slide onto stage
2-select lowest power objective lens
3-use coarse adjustment knob to move stage up the adjust to best focus
4-refine focus with fine adjustment knob
5-swap to higher power obl if needed
70
Q

mitotic index formula

A

number of cells with visible chromosomes/total number of cells observed

71
Q

where is EPG fitted

A

eye piece graticule fits onto eyepiece

72
Q

where is stage micrometer fitted

A

on the stage

73
Q

what are artefacts

A

things you see down the microscope which aren’t part of specimen eg. dust bubbles or fingerprint or inaccuracies caused by squashing/staining sample

74
Q

why are artefacts especially common in electron microscopes

A

specimens need a lot of preparation before being able to view under electron microscope

75
Q

how did first scientists stop artefacts

A

prepare samples in multiple ways and compare

BIOLOGY (20 decks)

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