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

2A: Cell structure & division Flashcards

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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
Q

Describe the cons of Transmission Electron Microscopes (TEM)

A
  • 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
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26
Q

Describe the pros of Scanning Electron Microscopes (SEM)

A
  • 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)
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27
Q

Describe the cons of Scanning Electron Microscopes (SEM)

A
  • cannot look at living cells
  • must be in a vacuum
  • complicated preparation may create artefact
  • does not produce a colour image
28
Q

What are the outer features of a prokaryotic cell.

A
  • Cell membrane / plasma membrane
  • Cell wall
  • Capsule
  • Pilus
  • Flagellum
29
Q

What can the cell membrane also be called? (pro)

A

Plasma membrane

30
Q

What is the cell wall made from? (pro)

A

Murein

31
Q

What is the function of the capsule? (pro)

A

Protects the cell

32
Q

What is the function of the pilus? (pro)

A

They help the cell attach to surfaces

33
Q

What is the function of the flagellum? (pro)

A

Allows for movement

34
Q

What is the function of the plasmids? (pro)

A

Secondary DNA storage

35
Q

What is the size of the ribosomes in prokaryotic cells compared to eukaryotic cells?

A

Ribosomes are smaller (20nm) in prokaryotic cells.

Ribosomes are bigger (25-30nm) in eukaryotic cells.

36
Q

What are the inner features of a prokaryotic cell?

A
  • Ribosomes
  • Cytoplasm
  • Large circular DNA strand
  • Plasmids
37
Q

What are the stages of cell fractionation?

A
  1. Cold, buffered, isotonic solution
  2. Homogenisation
  3. Tissue is sieved
  4. Ultracentrifugation
38
Q

Describe stage 1 of cell fractionation

A

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
Q

Describe stage 2 of cell fractionation

A

Homogenisation:

- Cells are broken up in a homogeniser (blender)

40
Q

Describe stage 3 of cell fractionation

A

Blended tissue is filtered through a sieve to remove insoluble material:

  • e.g cell walls
  • Large pieces of homogenised tissue
41
Q

Describe stage 4 of cell fractionation

A

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
Q

To convert mm –> um you x by ____

A

x 1000

43
Q

To convert um –> mm you / by ____

A

/1000

44
Q

What is cell differentiation?

A

Cell differentiation is the process by which cells become specialised for different functions.

45
Q

What is the function of attachment proteins? (v)

A

They allow the virus to attach to host cells

46
Q

What is the function of the lipid envelope? (v)

A

Derived from host cell membrane (easier attachment)

47
Q

What is the function of the capsid? (v)

A

Encapsulates the DNA/ RNA (protein coat)

48
Q

Describe the matrix in a virus

A

A protein layer on the inside of the envelope

49
Q

What are the 4 phases of mitosis?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
50
Q

What happens during mitosis?

A

Mitosis is the part of the cell cycle in which a eukaryotic cell divides once to produce two identical daughter cells.

51
Q

What happens during interphase?

what no. is it?

A
  1. Interphase:
    - The cell grows + replicates itself
    - The chromosomes are NOT visible
52
Q

What are the 6 phases of the cell cycle?

A
  1. Interphase
  2. Prophase
  3. Metaphase
  4. Anaphase
  5. Telophase
  6. Cytokinesis
53
Q

What happens during prophase?

what no. is it?

A
  1. Prophase:
    - Chromosomes condense and become visible
    - Centrioles move to poles + form spindle fibers
54
Q

What happens during metaphase?

what no. is it?

A
  1. Metaphase:
    - Chromosomes align along the equator
    - They become attached to the spindle fibers by their centromere
55
Q

What happens during anaphase?

what no. is it?

A
  1. Anaphase:
    - Centromeres split, allowing chromatids to separate
    - Chromatids move towards the poles pulled by the spindle fibers
56
Q

What happens during telophase?

what no. is it?

A
  1. Telophase:
    - Spindle fibers disperse
    - Nuclear envelope reforms
    - Chromosomes decondense
57
Q

What happens during cytokinesis?

what no. is it?

A
  1. Cytokinesis:

- A ring of protein filaments form around the equator of the cell, which then tightens and splits the cell in two

58
Q

What is cell division in prokaryotic cells called?

A

Binary fission

59
Q

What does binary fission involve?

A
  • 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
Q

What are the two types of tumour?

Describe them.

A

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
Q

What are the treatments for tumours?

A
  1. Surgery to remove tumours (mainly for benign)
  2. Radiotherapy (mainly for malignant)
  3. Chemotherapy
62
Q

Describe chemotherapy

A

Chemotherapy:

  • blocking enzymes involved in DNA synthesis
  • preventing DNA unwinding
  • Inhibiting synthesis of new nucleotides
  • preventing development of the spindle fibers
63
Q

What does radiotherapy do to the cells in the tumour(s)?

A

Radiotherapy damages the DNA of cells in the tumour(s)

64
Q

Which type of tumour is radiotherapy normally used for?

A

Malignant

65
Q

Which type of tumour is surgery (to remove the tumour) normally used for?

A

Benign

Biology A1 & A2 (19 decks)

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