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aqa a-level bio + chem + p.e. > Cell structure > Flashcards

Cell structure Flashcards

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1
Q

Describe the structure and function of the nucleus

A

Surrounded by a nuclear envelope
Nuclear pores allow substances to enter/exit
Contains DNA coiled into chromosomes
Controls the cell

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2
Q

Describe the structure and function of mitochondria

A

Cristae (site of ETC)
Matrix (contains DNA, lipids and proteins)
Site of aerobic respiration
Produces ATP

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3
Q

Describe the structure and function of the chloroplasts

A

Thylakoids (flattened stacked discs)
Stroma (fluid-filled matrix)
Site of photosynthesis
Converts solar energy to chemical energy

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4
Q

Describe the structure and function of the Golgi apparatus

A

Stack of membrane-bound, flattened sacs
Synthesises glycoproteins
Transports and stores proteins

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5
Q

Describe the structure and function of a lysosome

A

Sac surrounded by a glycoprotein coat
Exocytosis of digestive enzymes
Digests contents of phagosome

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6
Q

Describe the structure and function of a ribosome

A

Site of protein synthesis
In cytoplasm or attached to ER

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7
Q

Describe the structure and function of the endoplasmic reticulum (ER)

A

Rough ER = many ribosomes attached for protein synthesis
Smooth ER = lipid synthesis

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8
Q

Describe the structure of the cell wall in different organisms and functions it has

A

Bacteria = murein
Plants = cellulose microfibrils
Mechanical support
Physical barrier against pathogens
Enables easy diffusion

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9
Q

Describe the structure and function of the cell vacuole in plants

A

Absorbs and hydrolyses harmful substances
Acts as a temporary food source

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10
Q

State the role of plasmids, the flagella and the capsule in prokaryotes

A

Plasmids = small ring of DNA carrying non-essential genes
Flagella = tail that propels the organism
Capsule = provides mechanical support + acts as a food reserve

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11
Q

Compare and contrast eukaryotic and prokaryotic cells

A

Both have a cell membrane, ribosomes and cytoplasm
Eukaryotes: Prokaryotes:
multicellular unicellular
nucleus no nucleus
larger ribosomes smaller ribosomes
cellulose cell wall murein cell wall

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12
Q

What are viruses?

A

Viruses are acellular and non-living

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13
Q

Describe the structure of a virus

A

Attachment proteins on the surface
Capsid
Linear genetic material

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14
Q

What are the advantages and disadvantages of using an optical (light) microscope?

A

+ image in colour
+ relatively cheap equipment
- lower resolution than electron microscopes
- 2D image

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15
Q

What are the advantages and disadvantages of using a scanning electron microscope (SEM) ?

A

+ 3D image
+ higher resolution than optical
- requires a vacuum
- black and white image
- expensive

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16
Q

What are the advantages and disadvantages of using a transmission electron microscope (TEM) ?

A

+ higher resolution than optical
+ higher magnification than optical
- 2D image with no colour
- expensive
- longer process

17
Q

What happens during cell fractionation?

A
  1. Homogenize the tissue to release organelles
  2. Filter homogenate to remove debris
  3. Spin homogenate in centrifuge
  4. Most dense organelles form a pellet than can be filtered off
  5. It’s then spun again at a higher speed to remove any other organelles
18
Q

What are the stages in the cell cycle?

A

Interphase
Mitosis (nuclear division)
Cytokinesis (cytoplasmic division)

19
Q

What are the 3 stages that happen during interphase?

A

G1 = cell synthesises proteins for replication
S = DNA replicates
G2 = organelles divide

20
Q

What happens during the first phase of mitosis?

A

PROPHASE:
Chromosomes condense, becoming visible
Spindle fibres form

21
Q

What happens during the second phase of mitosis?

A

METAPHASE:
Sister chromatids line up along equator
Attached to spindles by their centromere

22
Q

What happens during the third stage of mitosis?

A

ANAPHASE:
Sister chromatids separate into 2 chromosomes
Centromeres divide

23
Q

What happens during the fourth stage of mitosis?

A

TELOPHASE:
Chromosomes decondense, becoming invisible
Spindle disintegrates

24
Q

How do cancer treatments control the rate of cell division?

A

Prevent DNA replication
Disrupt spindle formation

25
Q

How do prokaryotic cells replicate?

A

BINARY FISSION:
1. DNA loop replicates
2. Cell elongates, separating DNA loops
3. Cell membrane contracts
4. Cell splits into 2 identical cells with a DNA loop and varying number of plasmids

26
Q

How do viruses replicate?

A
  1. Attachment proteins attach to receptors on host cell
  2. Viruses fuse with cell membrane
  3. Host cell synthesises new viral proteins
  4. Components of the new viral particle assemble
27
Q

Why is it difficult to treat viruses?

A

They replicate inside living cells, making them difficult to kill without harming the host cell

aqa a-level bio + chem + p.e. (95 decks)

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