Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AS and A level > Biology AS Chapter 3 - Cell Structure > Flashcards

Biology AS Chapter 3 - Cell Structure Flashcards

1
Q

How do you calculate magnification?

A

Size of image / size of real object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is resolution?

A

The minimum distance apart 2 objects can be in order for them to appear separate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is cell fractionation?

A

The process where cells are broken up and the different organelles they contain are separated out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why must the solution the cells are placed in before cell fractionation be cold, buffered and isotonic?

A

Cold - reduce enzyme activity that might break down organelles
Isotonic - same water potential as the cell so organelles do not shrink or burst by osmosis
Buffered - so the pH does not fluctuate and alter organelle structure or enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is homogenation?

A

Cells are broken down by a homogeniser which releases the organelles from the cell. The resultant fluid, known as the homogenate, is then filtered to remove any complete cells or large pieces of debris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is ultracentrifugation?

A

The process by which the fragments in the filtered homogenate are separated in a centrifuge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the process of ultracentrifugation?

A
  • The tube of filtrate is placed in the centrifuge and spun at a slow speed
  • The heaviest organelles, the nuclei, are forced to the bottom of the tube where they form a thin sediment
  • The fluid at the top of the tube (supernatent) is removed, leaving the nuclei
  • The supernatent is transferred to another tube and spun in the centrifuge at a faster speed than before
  • The next heaviest organelle, the mitochondria, are forced to the bottom
  • The process is continued such that with each increase in speed, the next heaviest organelle is sedimented and separated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two main advantages of an electron microscope?

A
  • Electron beam has a very short wavelength and the microscope can therefore resolve objects well, it has a high resolving power
  • As electrons are negatively charged the beam can be focused using electromagnets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the parts of the nucleus and what do they do?

A
  1. Nuclear envelope - double membrane which controls the entry and exit of materials
  2. Nuclear pores - allow the passage of large molecules out of the nucleus
  3. Nucleoplasm - material that makes up bulk of nucleus
  4. Chromosomes - consist of protein bound, linear DNA
  5. Nucleolus - small region which manufactures ribosomal RNA and assembles the ribosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the functions of the nucleus?

A
  • act as the control centre of the cell through the production of mRNA and tRNA and hence protein synthesis
  • retain the genetic material of the cell in the form of DNA and chromosomes
  • manufacture rRNA and ribosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the parts of the mitochondria and what do they do?

A
  1. Double membrane - controls what enters and exits the cell
  2. Cristae - extensions of the inner membrane which provide a large surface area for the attachment of enzymes and proteins
  3. Matrix - contains proteins, lipids, ribosomes and DNA which allows the mitochondria to produce their own proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of the mitochondria?

A

The sites of aerobic respiration and are therefore responsible for the production of ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the parts of the chloroplasts what do they do?

A
  1. Chloroplast envelope - double plasma membrane that controls what enters and exits the cell
  2. Grana - stacks of thylakoids. Where the first stage of photosynthesis occurs
  3. Stroma - fluid filled matrix where the second stage of photosynthesis occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are chloroplasts adapted to their function of harvesting sunlight and carrying out photosynthesis?

A
  • Granal membranes provide a large SA for attachment of chlorophyll, electron carriers and enzymes
  • Stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis
  • Chloroplasts contain DNA and ribosomes so can quickly and easily manufacture some proteins needed in photosynthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the endoplasmic reticulum?

A

3D system of sheet like membranes which spreads through the cytoplasm of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the RER and its functions?

A

The RER has ribosomes on its outer surfaces of its membranes. Functions:
- provide a large SA for the synthesis of proteins and glycoproteins
- provide a pathway for the transport of materials throughout the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the SER and its functions?

A

The SER lacks ribosomes and is more tubular in appearance. Functions:
- synthesise, store and transport lipids and carbohydrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the structure of the golgi apparatus?

A

Consists of a stack of membranes that make up flattened sacs, or cristernae, with small rounded hollow structures called vesicles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the functions of the golgi apparatus?

A
  • add carbohydrate to proteins to form glycoproteins
  • produce secretory enzymes, such as those secreted by the pancreas
  • secrete carbohydrates
  • transport, modify and store lipids
  • form lysosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How are lysosomes formed?

A

When the vesicles produced by the Golgi apparatus contain enzymes, such as lysozymes which hydrolyse the cell walls of certain bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the functions of lysosomes?

A
  • hydrolyse material ingested by phagocytic cells, such as WBCs and bacteria
  • release enzymes to the outside of the cell in order to destroy material around the cell
  • digest worn out organelles so the useful chemicals they are made out of can be reused
  • completely break down cells after they have died (autolysis)
22
Q

What are the 2 types of ribosomes and where are they found?

A

80S - eukaryotic cells
70S - prokaryotic cells

23
Q

What is the function of a ribosome?

A

Site of protein synthesis

24
Q

What are the part of the cell wall?

A
  1. consist of a number of polysaccharides, such as cellulose
  2. there is a thin layer called the middle lamella which marks the boundary between adjacent cell walls and cements adjacent cells together
25
Q

What are the part of the cell wall?

A
  1. consist of a number of polysaccharides, such as cellulose
  2. there is a thin layer called the middle lamella which marks the boundary between adjacent cell walls and cements adjacent cells together
26
Q

What are the functions of the cell wall?

A
  • provide mechanical strength to prevent the cell bursting under the pressure created by the osmotic entry of water
  • give mechanical strength to the plant as a whole
  • allow water to pass along it and so contribute to the movement of water through the plant
27
Q

What is a vacuole?

A

A fluid filled sac bounded by a single membrane. The single membrane is called the tonoplast.

28
Q

What are the functions of the vacuole?

A
  • support herbaceous plants by making cells turgid
  • sugars and amino acids the store may act as a temporary food store
  • the pigments may colour petals to attract pollinating insects
29
Q

How does a cell become specialised?

A

Every cell contains the genes needed for it to develop into any one of the many different cells in an organism. Only some of these genes are switched on (expressed) in any one cell at any one time. Different genes are expressed in each type of specialised cell, the rest are switched off

30
Q

What is a tissue?

A

A collection of similar cells that perform a specific function

31
Q

Give 2 examples of a tissue, where they are found and their function

A
  1. Epithelial tissues - found in animals. They line the surfaces of organs and have a protective or secretory function
  2. Xylem - found in plants. Used to transport water and mineral ions throughout the plant, and provide mechanical support
32
Q

What is an organ?

A

A combination of tissues that are coordinated to form a variety of functions, although they often have one main function

33
Q

What tissues is the stomach make of?

A
  • muscle to churn and mix the stomach contents
  • epithelium to protect the stomach wall and produce secretions
  • connective tissues to hold together other tissues
34
Q

In a plant, what tissues make up an organ?

A
  • palisade mesophyll made up of leaf palisade cells which carry out photosynthesis
  • spongy mesophyll adapted for gaseous diffusion
  • epidermis to protect the leaf and allow gaseous diffusion
  • phloem to transport organic materials away from the leaf
  • xylem to transport water and ions into the leaf
35
Q

What is an organ system?

A

Organs work together as a single unit to perform particular functions

36
Q

What are the 3 organ systems in a human?

A
  1. digestive system - digests and processes food
  2. respiratory system - used for breathing and gas exchange
  3. circulatory system - pumps and circulates blood
37
Q

What is mitosis?

A

Cell division that produces two daughter cells that have the same number of chromosomes as the parent cell and each other

38
Q

What are the 5 stages of mitosis in order?

A

Interphase, prophase, metaphase, anaphase, telophase

39
Q

What happens in interphase?

A

Cell is actively synthesising proteins
Chromosomes invisible
DNA replicates

40
Q

What happens in prophase?

A

Chromosomes become visible
Nuclear envelope disintegrates
Nucleolus disappears

41
Q

What happens in metaphase?

A

Spindle fibres form
Chromosomes line up along the centre of the cell

42
Q

What happens in anaphase?

A

Spindle fibres attached to chromatids contract
Chromatids pulled towards poles

43
Q

What happens in telophase?

A

Chromosomes reach poles and become indistinct
Nuclear envelope reforms
Nucleolus reforms
Spindle fibres disintegrate

44
Q

What is cytokinesis?

A

The process of the cytoplasm dividing

45
Q

How do prokaryotic cells divide?

A

By binary fission

46
Q

What is the process of binary fission?

A
  • Circular DNA molecule replicates and both copies attach to the cell membrane
  • Plasmids also replicate
  • Cell membrane begins to grow between the two DNA molecules and begins to pinch inward, dividing the cytoplasm into two
  • As the new cell wall forms between the two molecules of DNA, dividing the original cell into 2 identical daughter cells, each with a single copy of circular DNA and a variable number of plasmids
47
Q

How do viruses replicate?

A

They attach to their host cell via the attachment proteins on their surface. They then inject nucleic acid into the host cell. The genetic information on the injected viral nucleic acid provide instructions for the host cells metabolic processes to start producing viral components which are then assembled into new viruses

48
Q

What is cancer?

A

A group of diseases caused by a growth disorder of cells. It is the result of damage to the genes that regulate mitosis and the cell cycle. This leads to uncontrolled growth and division of cells

49
Q

How does a tumour become cancerous?

A

If it changes from benign to malignant

50
Q

How does the treatment of cancer work?

A

Involves killing dividing cells by blocking a part of the cell cycle, meaning cell division ceases

51
Q

How do drugs used to treat cancer usually disrupt the cell cycle?

A
  • preventing DNA from replicating
  • inhibiting the metaphase stage of mitosis by interfering with spindle formation

AS and A level (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions