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A Level Biology > Cell Structure And Cell Cycle > Flashcards

Cell Structure And Cell Cycle Flashcards

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1
Q

PMATC

A

Prophase metaphase anaphase telophase cytokinesis

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2
Q

Prophase

A

Chromatin condenses and chromosomes become visible
Nucleoli disappears
Nuclear membrane disappears
Centrioles move to poles of cell to form spindle fibres called kinetichore
Chromosomes attach to spindle fibres at centromere.

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3
Q

Metaphase

A

Chromosomes (made up of two sister chromatids) line up on the equator of spindle fibres
The microtubules of the spindle are attached to the centromere of each chromosome

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4
Q

Centrioles are different from centromeres

A

Centriole floats in nucleoplasm and forms spindle when needed
Centromeres of chromosome attach to spindle microtubules

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5
Q

Anaphase

A

Centromeres divide and spindle fibres begin to shorten
Sister chromatids are pulled to opposite poles by spindles using energy from ATP (produced by mitochondria)
Separated chromatids are referred to as separate chromosomes.

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6
Q

Telophase

A

Chromosomes reach poles
Chromosomes decondense so are no longer visible
Spindle breaks down and centrioles reappear
Nuclear membrane reappears
Nucleoli reappear

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7
Q

Cytokinesis

A

Cytoplasm splits along with cell membrane and nucleus.

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8
Q

Chromosomes,chromatin,chromatid difference

A

Chromatin - decondensed, unravelled, before mitosis in interphase and semi conservative replication.
Chromosomes are only seen during cell division
Chromatid is one dna molecule and two form a chromosomes
Called chromatids as soon as chromatin condenses.

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9
Q

mitotic Index

A

% of cells in mitosis

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10
Q

Mitosis is a controlled process because

A

There are four checkpoints:
G0 = resting state
G1= check for nutrients,growth factors and dna damage
Then S is dna synthesis
Then G2 is check for cells size and dna replication
Then metaphase checkpoint checks for chromosome spindle attachment
Then G1 begins

Cyclin proteins control the cell cycle

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11
Q

Apoptosis is

A

Programmed cell death

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12
Q

Cyclin proteins

A

Control the cell cycle

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13
Q

Tumours and cancers are formed by

A

Uncontrolled cell division

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14
Q

How to treat cancer

A

Chemotherapy is the injection of drugs that inhibit DNA replication/ spindle formation for example colchacine

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15
Q

Binary fission is cell for what type of cells

A

Prokaryotes like bacteria

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16
Q

What is binary fission

A

Replication of circular DNA and plasmids

Then the division of cytoplasm to produce two daughter cells

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17
Q

How do bacterial cells multiply and give formula to find the number of cells (N) after (n) generations (N0 is initial number at time 0)

A

N=N0x2^n

Exponentially

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18
Q

Embryonic/Adult stem cells

A 
Early embryo (four days) 
Unspecialised cells undergo differentiation to become specialised. All contain the same genetic information but different genes are expressed differently.
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19
Q

Specialised cell

A

Gene expression causes cell specialisation

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20
Q

Differences between meiosis and mitosis

A

Meiosis = 4 genetically different daughter cells whereas mitosis produces two genetically different daughter cells
Meiosis produces gametes for sexual reproduction
Mitosis is for growth/repair/sexual reproduction
Mitosis has 46 chromosomes and are diploid
Meiosis produces 23 chromosomes hence haploid that become diploid when fuses with opposite gamete
Meiosis has two divisions of cytoplasm in one cycle whereas mitosis only has one

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21
Q

How is skin surface replaced after sloughing

A

Adult stem cells replace cells lost

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22
Q

Golgi vesicles function

A

Store and transport lipids and proteins made by the golgi apparatus

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23
Q

Golgi vescicle structure

A

Phospholipid bilayer (double membrane)

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24
Q

Lysosomes are

A

Tiny sac of digestive enzymes, surrounded by a single membrane

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25
Q

Function of lysosomes

A

Hydrolyse material ingested by phagocytes
Exocytosis release enzymes to the outside of cells and destroy material around the cell
Digest worn out organelles so useful chemicals can be used
Autolysis = cells broken down completely after they have dies

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26
Q

What is autolysis

A

Complete break down of cells after they have died

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27
Q

Exoctyosis

A

Bulk transport of material out of cell using vesicles

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28
Q

Endocytosis

A

Bulk transport of material into cell using vesiclese

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29
Q

What does the endoplasmic reticulum look like

A

Made up of flattened membrane bound sacs called cisternae

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30
Q

What is on the surface of rough ER

A

Ribosomes

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31
Q

What does the rough ER do

A

Modifies and transports proteins made from the ribosomes

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32
Q

Function of smooth ER

A

Suthesis and processes lipids

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33
Q

Smooth ER in liver cells do what?

A

Break down toxins

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34
Q

What is multicellularity

A

Division of labour between cells

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35
Q

What is a tissue

A

One type of specialised cells

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36
Q

What is an organ

A

Severa, tissues

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37
Q

What is blood 🩸

A

A tissue

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38
Q

What does the golgi look like

A

Unstable structure = constantly changing

Stacks of membrane bound flattened sacs

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39
Q

What does the golgi do

A 
Receives proteins from ER 
Modifies proteins 
Processes and packages them into vescicle 
Vesicles are moved to plasma membrane 
Exocytosis 
Also add carbohydrates to proteins to form glycoproteins 
Produce secretary enzymes 
Secrete carbs
Form lysosomes 
Transport modify and store lipids
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40
Q

Plant Cell wall looks

Like and function

A

Line (middle lamedla is the junction of two cell walls)

Provides rigidity and strength to the cell to prevent bursting under pressure created by osmotic entry of water

41
Q

plant cell is made opus of what which is a what

A

Cellulose

Polysaccharide

42
Q

Cell wall of algae

A

Cellulose/glycoproteins

43
Q

Cell wall of fungi

A

Chitin polysaccharide

44
Q

Vacuole function and look alike

A

Fluid filled sac bound by a single membrane called tonoplast
Support to plant cells
Temporary food store
Pigments may colour petals to attract pollinating insects

45
Q

Ribosomes are, —-,size,which is found where and what does it look like and do

A 
Small cytoplasmic granules 
Found in all cells 
Two types 80S which is around 25nm in eukaryotes and 70S which is slightly smaller and in prokaryotes 
Two subunits - one large and one small 
Ribosomal RNA and protein in both 
Protein synthesis
46
Q

Prokaryotic organisms description

A

Unicellular, no nucleus or membrane bound organelles like bacteria or archaea

47
Q

Eukaryotes did what after prokaryotes

A

Evolved - are more evolved

48
Q

Prokaryotes cell wall made of

A

Muréin for shape and protection

49
Q

What is a messasome, it’s purpose and where is it found

A

Inward folded piece of membrane
Increases SA for reactions
Found in eukaryotes

50
Q

Prokaryotes contain what organelles

A

Flagellum for movement
Pillí - movement and adherence to surfaces
Slime capsule - stop invading phagocytes
70S ribosomes
Cytoplasm
Cell membrane
Cell wall
Double stranded dna and nuclei of containing GM in circular loops called plasmids

51
Q

Bacteria contain plasmids purpose

A

Useful for genetic engineering

Extra chromosomal dna

52
Q

Nucleus

A 
10 micrometers to 20 micrometers 
Nuclear envelope 
Nuclear pore 
Nucleoplasm 
Chromosomes 
Nucleolus
53
Q

Nuclear envelope

A

Double membrane
Outer is continuous with ER
Controls and regulate movement of in and out of organelle

54
Q

Nuclear pores

A

Allows passage of large molecules like RNA around 300nm

55
Q

Nucleoplasm

A

Jelly like material that makes up bulk of nucleus

56
Q

Nucleoli

A

Manufacture ribosomal RNA and assembles ribosomes

57
Q

What is magnification

A

How much bigger an image is to reality

58
Q

What is resolution

A

The smallest distance an visible between two dots

59
Q

How does a light microscope work

A

Rays of light hit specimenand are seen through eyepiece

60
Q

Pros of light microscope

A

Easy and cheap to operate

Living specimens as well

61
Q

Cons of optical microscope

A

Low resolution and magnification - can’t see organisms smaller than 0.2 micrometers
Specimens often need staining to show specific organelles

62
Q

Long wavelength of light rays mean

A

Smaller organelles aren’t visible

63
Q

Two types of electron microscope

A

Transmission

Scanning

64
Q

How do transmission electron microscope work

A

Use electromagnets to focus a beam of electorons which are then transmitted into specimen
Denser parts absorb more electrons hence appear darker in black and white image

65
Q

Max resolution for transmission electron microscope

A

0.1nm

66
Q

Max resolution transmission electron microscope

A

10,000,000

67
Q

Pro of transmission electron

A

Highest resolution and magnification

68
Q

4 cons of TEM

A 
Non living matter 
2D black and white 
Staining of heavy metals hence artefacts may form 
Vacuum 
Elebaorate staining
69
Q

How does scanning electron microscope work

A

Scan beam of electrons across specimen and knock electrons off it
Electrons gather in cathode ray tube to form image

70
Q

Max magnification of SEM

A

30,000

71
Q

Max resolution of SEM

A

20nm

72
Q

3 pros of SEM

A

Complex 3D images are formed
Works on their specimens
Higher msg and res than light microscope

73
Q

3 cons SEM

A

Large expensive hard to operate
Mounted in vacuum
Has to be dead specimen

74
Q

Image equation

A

Image = actual x magnification

75
Q

Cell fractionation steps

A

Tissue is cut up and kept in a cold isotonic buffered isolation medium (solution)
Then further broken in homogeniser
Then spun in ultracentrifuge for 10 mins at low speed
Súpernatant is removed and pellet is spun at medium speed then higher speed to obtain sediment of chloroplast

76
Q

What are the isolation mediums have three requirements and why

A

Cold = slows enzyme action
Isotonic (same water potential) = keeps membrane stable so no bursting or shrivelling
Buffered = keeps ph stable

77
Q

3 condensed steps cell fractionation

A

Homogenisation
Filtration
Ultracentrifugation

78
Q

Eukaryotic cells vs prokaryotic cells

A 
Nucleus vs no nucleus but has plasmids instead 
HISTONE ASSOCIATE DNA VS DNA 
introns vs no introns so no splicing
Membrane bound organelles vs no membrane bound organelles 
No Slime capsule vs slime capsule 
Chloroplasts vs no chloroplast 
No pilli vs pilli 
Sometimes flagellum vs sometimes flagellum 
Either unicellular or multi vs only uni 
Big vs small 
80S ribosomes vs 70S ribosomes 
Chromatin vs no chromatin 
Cellulose cell wall vs murein cell wall
No mesasome vs mesasome
79
Q

Why is dna in bacterium called naked

A

No chromatin

80
Q

Endosymbiosis theory

A

Eukaryotes evolved from a prokaryotic ancestor

81
Q

Endosymbiosis theory stages examples

A

Ancestral prokaryote, infolding of plasma membrane creates a compartment for nucleoid which is likely to be Arachaea
Then aerobic bacteria is consumed (cynaobacterium as well) this is the endosymbiosis
Then ancestral eukaryote instead of breaking down consumed bacteria, it stays with the eukaryote and form chloroplast and mitochondria so are protected

82
Q

The ancestral eukaryote and chloroplast and mitochondria live in —— and explain

A

Symbiosis where both benefit

83
Q

Parasitises

A

One organisms deprives the other of nutrients “abuse”

84
Q

Bacteria evolved into —— making

A

Mitochondria hence produce energy making human cells possible

85
Q

Chloroplast and mitochondria features that looks like prokaryotes

A

Contain circular DNA
70S ribosomes
Double membrane - inner looks like bacteria outer looks like plant cells
Similar size to prokaryotes

86
Q

Mitochondria description and function

A

Highly folded inner membrane called cristae
Enzymes for respiration in membrane
Watery region called matrix
ATP synthase in cristae (stalked particles)

Site of aerobic respiration providing energy in the form of ATP

87
Q

How is mitochondria adapted for its function

A

Folded inner membrane called cristae creates large surface area for aerobic respiration to occur efficiently
Enzymes for respiration in membrane to speed up process without getting used up

88
Q

Chloroplasts description and purpose

A

Stroma- watery region where second stage of photosynthesis occurs - the synthesis of sugars made from enzymes
Thylakoid membrane bridges gap between grana
Grana is stack of membrane
Stalked particles found in thylakoid membrane
Chloroplast envelope contains double membrane that is highly selective about movement into and out of organelle

89
Q

Viruses are

A

Acellular hence no structure and neither prokaryotic or eukaryotic

90
Q

MRS GREN for viruses do which of them

A

Reproduce

Sensitivity - attach to cell

91
Q

Viral genetic material

A

Could be dna (2 strands) or found as rna (one strand)

Packaged in protein head called capsid

92
Q

Virus structure

A

Nuclei acid surrounded by protein capsid a matrix and a lipid envelope with attachment proteins.

93
Q

Viral replication

A

Virus attaches to host cell and injects Genetic material
GM used as code to synthesise more nuclei acids and proteins
New Viruse particles are assembles
Viruses burst out and destroy cell

94
Q

Plant organs

A

Palisade myseophyll made out of palisade cells on leaf for photosynthesis
Spongy myseophyll for gasesous diffusion
Epidermis is protection and gas diffusion
Phloem transports sugars away from leaf
Xylem transports water to leaf

95
Q

Danger of using chemo

A

Affect normal cell cycle

96
Q

Why are large mammals made out of small cells

A

So there is enough SA to absorb nutrients and let go off waste quickly
Unicellular organism as large as elephant can not exist as the exact he of materials would not be quick enough

97
Q

Cell surface membrane structure

A

Phospholipid bilateral with fatty acid tails facing each other. Cholestrol in plants. Fluid Mosaic. Protein carriers and channel. Glycolipids and glycoproteins

98
Q

Bacterial DNA vs human DNA differences

A

Naked dna
Linear/plasmids
No histones vs histones
Binary fission vs mitosis

A Level Biology (18 decks)

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