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A Level Biology > Cell Structure And Cell Cycle > Flashcards

Cell Structure And Cell Cycle Flashcards

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
Function of lysosomes
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
26
What is autolysis
Complete break down of cells after they have died
27
Exoctyosis
Bulk transport of material out of cell using vesicles
28
Endocytosis
Bulk transport of material into cell using vesiclese
29
What does the endoplasmic reticulum look like
Made up of flattened membrane bound sacs called cisternae
30
What is on the surface of rough ER
Ribosomes
31
What does the rough ER do
Modifies and transports proteins made from the ribosomes
32
Function of smooth ER
Suthesis and processes lipids
33
Smooth ER in liver cells do what?
Break down toxins
34
What is multicellularity
Division of labour between cells
35
What is a tissue
One type of specialised cells
36
What is an organ
Severa, tissues
37
What is blood 🩸
A tissue
38
What does the golgi look like
Unstable structure = constantly changing | Stacks of membrane bound flattened sacs
39
What does the golgi do
``` 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 ```
40
Plant Cell wall looks | Like and function
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
plant cell is made opus of what which is a what
Cellulose | Polysaccharide
42
Cell wall of algae
Cellulose/glycoproteins
43
Cell wall of fungi
Chitin polysaccharide
44
Vacuole function and look alike
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
Ribosomes are, —-,size,which is found where and what does it look like and do
``` 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
Prokaryotic organisms description
Unicellular, no nucleus or membrane bound organelles like bacteria or archaea
47
Eukaryotes did what after prokaryotes
Evolved - are more evolved
48
Prokaryotes cell wall made of
Muréin for shape and protection
49
What is a messasome, it’s purpose and where is it found
Inward folded piece of membrane Increases SA for reactions Found in eukaryotes
50
Prokaryotes contain what organelles
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
Bacteria contain plasmids purpose
Useful for genetic engineering | Extra chromosomal dna
52
Nucleus
``` 10 micrometers to 20 micrometers Nuclear envelope Nuclear pore Nucleoplasm Chromosomes Nucleolus ```
53
Nuclear envelope
Double membrane Outer is continuous with ER Controls and regulate movement of in and out of organelle
54
Nuclear pores
Allows passage of large molecules like RNA around 300nm
55
Nucleoplasm
Jelly like material that makes up bulk of nucleus
56
Nucleoli
Manufacture ribosomal RNA and assembles ribosomes
57
What is magnification
How much bigger an image is to reality
58
What is resolution
The smallest distance an visible between two dots
59
How does a light microscope work
Rays of light hit specimenand are seen through eyepiece
60
Pros of light microscope
Easy and cheap to operate | Living specimens as well
61
Cons of optical microscope
Low resolution and magnification - can’t see organisms smaller than 0.2 micrometers Specimens often need staining to show specific organelles
62
Long wavelength of light rays mean
Smaller organelles aren’t visible
63
Two types of electron microscope
Transmission | Scanning
64
How do transmission electron microscope work
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
Max resolution for transmission electron microscope
0.1nm
66
Max resolution transmission electron microscope
10,000,000
67
Pro of transmission electron
Highest resolution and magnification
68
4 cons of TEM
``` Non living matter 2D black and white Staining of heavy metals hence artefacts may form Vacuum Elebaorate staining ```
69
How does scanning electron microscope work
Scan beam of electrons across specimen and knock electrons off it Electrons gather in cathode ray tube to form image
70
Max magnification of SEM
30,000
71
Max resolution of SEM
20nm
72
3 pros of SEM
Complex 3D images are formed Works on their specimens Higher msg and res than light microscope
73
3 cons SEM
Large expensive hard to operate Mounted in vacuum Has to be dead specimen
74
Image equation
Image = actual x magnification
75
Cell fractionation steps
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
What are the isolation mediums have three requirements and why
Cold = slows enzyme action Isotonic (same water potential) = keeps membrane stable so no bursting or shrivelling Buffered = keeps ph stable
77
3 condensed steps cell fractionation
Homogenisation Filtration Ultracentrifugation
78
Eukaryotic cells vs prokaryotic cells
``` 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
Why is dna in bacterium called naked
No chromatin
80
Endosymbiosis theory
Eukaryotes evolved from a prokaryotic ancestor
81
Endosymbiosis theory stages examples
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
The ancestral eukaryote and chloroplast and mitochondria live in —— and explain
Symbiosis where both benefit
83
Parasitises
One organisms deprives the other of nutrients “abuse”
84
Bacteria evolved into —— making
Mitochondria hence produce energy making human cells possible
85
Chloroplast and mitochondria features that looks like prokaryotes
Contain circular DNA 70S ribosomes Double membrane - inner looks like bacteria outer looks like plant cells Similar size to prokaryotes
86
Mitochondria description and function
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
How is mitochondria adapted for its function
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
Chloroplasts description and purpose
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
Viruses are
Acellular hence no structure and neither prokaryotic or eukaryotic
90
MRS GREN for viruses do which of them
Reproduce | Sensitivity - attach to cell
91
Viral genetic material
Could be dna (2 strands) or found as rna (one strand) | Packaged in protein head called capsid
92
Virus structure
Nuclei acid surrounded by protein capsid a matrix and a lipid envelope with attachment proteins.
93
Viral replication
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
Plant organs
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
Danger of using chemo
Affect normal cell cycle
96
Why are large mammals made out of small cells
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
Cell surface membrane structure
Phospholipid bilateral with fatty acid tails facing each other. Cholestrol in plants. Fluid Mosaic. Protein carriers and channel. Glycolipids and glycoproteins
98
Bacterial DNA vs human DNA differences
Naked dna Linear/plasmids No histones vs histones Binary fission vs mitosis

A Level Biology (18 decks)

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