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Biology A1 & A2 > 2A: Cell structure & division > Flashcards

2A: Cell structure & division Flashcards

1
Q

Describe the Nuclear Envelope

A

Encases the nucleus

2 lipid bilayer membranes

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2
Q

Describe the Nuclear Pores

A

Transports molecules across the nuclear envelope

E.g RNA out, proteins in

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3
Q

Describe the Nucleoplasm

A

The substance in the nucleus

Includes chromosomes and nucleolus

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4
Q

Describe the Chromosomes

A

Made up of nucleic acid and proteins

Carries genetic information in the form of genes

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5
Q

Describe the Nucleolus

A

Largest structure in the nucleus

Makes ribosomes

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6
Q

What does the nucleus consist of? (5)

A
  1. Nuclear envelope
  2. Nuclear pores
  3. Nucleoplasm
  4. Chromosomes
  5. Nucleolus
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7
Q

Describe the Double Membrane (mitochondria)

A

Outer membrane: like a skin

Inner membrane: folded into layered structures which increase surface area

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8
Q

Describe the Cristae (mitochondria)

A

The folds made by the inner membrane

More space for chemical reactions

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9
Q

Describe the Matrix (mitochondria)

A

Fluid contained within mitochondria
Ribosomes + DNA floating in it
Contains granules which help with ion concentrations

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10
Q

What do the mitochondria consist of? (3)

A
  1. Double membrane
  2. Cristae
  3. Matrix
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11
Q

Describe the Rough Endoplasmic Reticulum

A

Contains ribosomes for protein synthesis

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12
Q

Describe the Smooth Endoplasmic Reticulum

A

Lipid and carbohydrate synthesis

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13
Q

Describe the Golgi Apparatus (+ Vesicles)

A

Where things are ‘packaged’ and transported to other parts of the cell (secreted)
Makes lysosomes

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14
Q

Describe the cytoplasm

A

Jelly like substance
Where most chemical reactions in the cell take place
The site of anaerobic respiration

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15
Q

Describe the Cell Membrane

A

Allows molecules in and out of the cell

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16
Q

Describe the lysosomes.

Where are they made?

A

They contain strong digestive enzymes to digest waste e.g broken cell organelles, pathogens

Made in the Golgi Apparatus

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17
Q

Describe the Ribosomes

A

Where protein synthesis takes place

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18
Q

Describe the Cell Wall

A

Made of cellulose

Strengthens the cell

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19
Q

Describe the Vacuoles

A

Stores cell sap

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20
Q

Describe the Chloroplast Envelope

A

Similar structure to the mitochondria double membrane (except not folded)

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21
Q

Describe the Grana

A

Made up of stacks of discs called thylakoids (resembles a stack of coins)
Site of light- dependent reactions of photosynthesis
Connected by intergranal thylakoids

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22
Q

Describe the Stroma

A

Colourless fluid surrounding grana
Contains enzymes required for LIR of photosynthesis
DNA + ribosomes are also present

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23
Q

What does a chloroplast consist of? (3)

A
  1. Chloroplast Envelope
  2. Grana
  3. Stroma
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24
Q

Describe the pros of Transmission Electron Microscopes (TEM)

A
  • high magnification
  • highest resolution (due to shorter wavelength of electrons)
  • produces a 2D photomicrograph, on a screen (the electrons are transmitted through the specimen)
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25
Describe the cons of Transmission Electron Microscopes (TEM)
- cannot look at living cells - must be in a vacuum - must cut section / have a thin specimen - complicated preparation may create artefact - does not produce a colour image
26
Describe the pros of Scanning Electron Microscopes (SEM)
- high magnification - specimen does not need to be thin - focuses using condenser electromagnet - produces a 3D image (the electrons are directed at the specimen and bounce off)
27
Describe the cons of Scanning Electron Microscopes (SEM)
- cannot look at living cells - must be in a vacuum - complicated preparation may create artefact - does not produce a colour image
28
What are the outer features of a prokaryotic cell.
- Cell membrane / plasma membrane - Cell wall - Capsule - Pilus - Flagellum
29
What can the cell membrane also be called? (pro)
Plasma membrane
30
What is the cell wall made from? (pro)
Murein
31
What is the function of the capsule? (pro)
Protects the cell
32
What is the function of the pilus? (pro)
They help the cell attach to surfaces
33
What is the function of the flagellum? (pro)
Allows for movement
34
What is the function of the plasmids? (pro)
Secondary DNA storage
35
What is the size of the ribosomes in prokaryotic cells compared to eukaryotic cells?
Ribosomes are smaller (20nm) in prokaryotic cells. | Ribosomes are bigger (25-30nm) in eukaryotic cells.
36
What are the inner features of a prokaryotic cell?
- Ribosomes - Cytoplasm - Large circular DNA strand - Plasmids
37
What are the stages of cell fractionation?
1. Cold, buffered, isotonic solution 2. Homogenisation 3. Tissue is sieved 4. Ultracentrifugation
38
Describe stage 1 of cell fractionation
Place cells in a cold, buffered, isotonic solution: - Cold- reduces enzyme activity - Buffered- maintains constant pH and prevents protein damage - Isotonic- to prevent organelles bursting or shrinking
39
Describe stage 2 of cell fractionation
Homogenisation: | - Cells are broken up in a homogeniser (blender)
40
Describe stage 3 of cell fractionation
Blended tissue is filtered through a sieve to remove insoluble material: - e.g cell walls - Large pieces of homogenised tissue
41
Describe stage 4 of cell fractionation
Ultracentrifugation: - The filtrate is placed in a centrifuge and spun at a slow speed - The heaviest organelles are forced to the bottom - The fluid at the top is then removed - Repeat at a higher speed (organelles get lighter)
42
To convert mm --> um you x by ____
x 1000
43
To convert um --> mm you / by ____
/1000
44
What is cell differentiation?
Cell differentiation is the process by which cells become specialised for different functions.
45
What is the function of attachment proteins? (v)
They allow the virus to attach to host cells
46
What is the function of the lipid envelope? (v)
Derived from host cell membrane (easier attachment)
47
What is the function of the capsid? (v)
Encapsulates the DNA/ RNA (protein coat)
48
Describe the matrix in a virus
A protein layer on the inside of the envelope
49
What are the 4 phases of mitosis?
1. Prophase 2. Metaphase 3. Anaphase 4. Telophase
50
What happens during mitosis?
Mitosis is the part of the cell cycle in which a eukaryotic cell divides once to produce two identical daughter cells.
51
What happens during interphase? | what no. is it?
1. Interphase: - The cell grows + replicates itself - The chromosomes are NOT visible
52
What are the 6 phases of the cell cycle?
1. Interphase 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase 6. Cytokinesis
53
What happens during prophase? | what no. is it?
2. Prophase: - Chromosomes condense and become visible - Centrioles move to poles + form spindle fibers
54
What happens during metaphase? | what no. is it?
3. Metaphase: - Chromosomes align along the equator - They become attached to the spindle fibers by their centromere
55
What happens during anaphase? | what no. is it?
4. Anaphase: - Centromeres split, allowing chromatids to separate - Chromatids move towards the poles pulled by the spindle fibers
56
What happens during telophase? | what no. is it?
5. Telophase: - Spindle fibers disperse - Nuclear envelope reforms - Chromosomes decondense
57
What happens during cytokinesis? | what no. is it?
6. Cytokinesis: | - A ring of protein filaments form around the equator of the cell, which then tightens and splits the cell in two
58
What is cell division in prokaryotic cells called?
Binary fission
59
What does binary fission involve?
- Replication of the circular DNA and of plasmids - Division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.
60
What are the two types of tumour? | Describe them.
Benign: slow growing, does not spread and is not classed as a cancer Malignant: fast growing, does spread and is classed as a cancer
61
What are the treatments for tumours?
1. Surgery to remove tumours (mainly for benign) 2. Radiotherapy (mainly for malignant) 3. Chemotherapy
62
Describe chemotherapy
Chemotherapy: - blocking enzymes involved in DNA synthesis - preventing DNA unwinding - Inhibiting synthesis of new nucleotides - preventing development of the spindle fibers
63
What does radiotherapy do to the cells in the tumour(s)?
Radiotherapy damages the DNA of cells in the tumour(s)
64
Which type of tumour is radiotherapy normally used for?
Malignant
65
Which type of tumour is surgery (to remove the tumour) normally used for?
Benign

Biology A1 & A2 (19 decks)

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