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Cell Biology Flashcards

0
Q

Cell wall?

A

Semi rigid structure composed mainly of cellulose.

Supports cell and limits its volume.

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1
Q

What are the 4 plant phyla?

A

Bryophyta (moss)
Filicinophyta (fern)
Coniferophyta (christmas tree)
Angiospermophyta (daffodil)

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2
Q

Ribosomes?

A

Site of protein synthesis,

Can be free in cytoplasm or associated with the ER

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3
Q

Endoplasmic reticulum:

A

Network of tubes and flattened sacs. May be smooth or have attached ribosomes
(In plant cell can be rough or smooth)

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4
Q

Mitochondria?

A

They are the cell energy transformers, converting chemical energy into ATP. (Site of aerobic respiration)
Consist of matrix (with fluid) and cristae (folds)

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5
Q

Starch granules?

A

Carbohydrates stored in amyloplasts (plasmids for specialised storage)

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6
Q

Chloroplast?

A

Specialised plasmids containing chlorophyll.
Site of photosynthesis.
Contain grana (dense stacks of thylacoids) within a colourless stroma

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7
Q

Golgi apparatus

A

A series of flattened disc shaped sacs (vescicles and cisterna)
It stores, modifies and packages proteins.

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8
Q

Vacuoles?

A

Large central v: filled with an aqueous solution of ions, for storage, waste disposal and growth.

Other: in animal cells, they are smaller

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9
Q

Nucleolus?

A

A dense solid structure composed of crystalline protein and nucleic acid.
Contains chromosomes that carry genetic information.

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10
Q

Lysosome?

A

(In animal cells)
Formed with the golgi apparatus.
Contain and transport enzymes that break down food and foreign matter.

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11
Q

Centrioles and microtubules

A

M: move chromosomes during cell division
C: composed of Microtubules, form an anchor point for them during cell division

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12
Q

Difference between prokaryotic and eukaryotic cells?

A

P are smaller; E larger
P unicellular; E often multicellular
P has no nucleus (naked DNA called nucleiod); E has nucleus
P can have flagella/pili; E has organelles
P has plasmids (circular DNA); E has linear
P divides by binary fission; E by mitosis/meiosis(sex)
P contains 70s ribosomes; E contains 80s

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13
Q

What is the cell theory?

A

The theory that cells are the fundamental building blocks of all living organisms

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14
Q

Limitations on cell size?

A

Rate of metabolic reactions is proportional to volume, the rate of absorption depends on SA.
Therefore, SA:volume is important.

The larger the animal, the smaller the SA, so the smaller the metabolic rate.

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15
Q

How to calculate magnification and units of size?

A

Magn= size of image/size of specimen

1000mm = 1m
1000μm = 1mm
1000nm = 1μm
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16
Q

What are stem cells?

A

Cells that can differentiate to form specialised cells.

They have the ability to divide for growth and repair.

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17
Q

Advantages of embryonic vs adult stem cells?

A

Embryonic:
Easier to obtain.
Almost unlimited growth potential as they are undifferentiated.
Less chance of genetic damage.

Adult:
No embryo must be destroyed to obtain them.
Cells have no rejection problems with adult tissue.
There is less chance of malignant tumours called teratocarcinomas

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18
Q

Case study of the therapeutic use of adult stem cells?

A

Leukaemia: the production of abnormally large numbers of white blood cells.

  1. Stem cells are removed from bone marrow and stored
  2. Chemotherapy kills cancer cells
  3. Healthy cells are inserted back in to multiply
19
Q

Case study of the therapeutic use of embryonic stem cells?

A

Stargardt’s: a recessive mutation in the retina caused by the presence of gene ABCA4

This disease causes a membrane protein used for active transport in retina cells to malfunction. Toxins then build up and photoreceptive cells in the retina degenerate.

Embryonic stem cells first used on a woman in the U.S. In 2010

20
Q

Go study the fluid mosaic model

A

30th september 2014

21
Q

Endocytosis?

Exocytosis?

A

Bringing materials into/out of the cell using vesicles (a membrane bound package). Enzymes then digest what is inside the packages by hydrolysing them. Lysosomes then open up the vesicles.

22
Q

Pinocytosis?

A

Invaginations that take in extra cellular fluid which contain particles.
AKA ‘cell drinking’

23
Q

Phagocytosis?

A

When a solid particle is engulfed by the pseudopodium to become a phagosome (food vacuole).
AKA ‘cell eating’

24
Receptor mediated endocytosis?
Special form of pinocytosis which involved receptors picking up specific particles and has a protein coating
25
Functions of membrane bound proteins?
- hormone binding site (e.g. Insulin receptor) - immobilised enzymes with the active site in the outside (e.g. Small intestine) - cell adhesion to form tight junctions between groups of cells (e.g. In cell tissues) - cell to cell communication (e.g. Receptors for neurotransmitters at synapses) - channels got passive transport to allow hydrophilic particles across by facilitated diffusion - pumps for active transport which use ATO to move particles across the membrane
26
Examples of passive transport?
Simple diffusion Facilitated diffusion Osmosis
27
What is passive transport?
The movement of substances down a concentration gradient (no ATP needed) Normally through phospholipids but is sometimes through protein pores in facilitated diffusion
28
Hypotonic, isotonic and hypertonic?
Hypo- high WP outside, low WP inside (water moves in) Isotonic- equal WP (no net water movement) Hyper: low WP outside, high WP inside (water moves out)
29
What is active transport?
The movement of particles against a concentration gradient (so ATP is needed)
30
What is the sodium potassium pump?
See notes on 7th october
31
What are the stages of cell division?
``` Interphase (growth, synthesis and growth) Mitotic phase (prophase, metaphase, anaphase and telophase) ```
32
What is the first part of interphase? (Growth1)
- New proteins are synthesised - rRNA, mRNA, tRNA produced to make them - cell organelles produced
33
What is the second part of interphase? (Synthesis)
- DNA replication occurs - 2 sister chromatids formed NB: telomere = end of the chromosome
34
What is the third part of interphase? (Growth2)
- centrioles replicate (animal cells only) - mitotic spindle of microtubules is formed - mitochondria (and chloroplasts) divide
35
What happens in prophase?
* Sister chromadids become visable as thread-like structures --> supercoil * Nucleus starts to disappear * Microtubules initiate spindle formation and determine the poles * Clusters of microtubules form around the centrioles (poles) * The nuclear membrane degrades
36
What happens in metaphase?
* The spindle apparatus moves chromosomes to the equator | * The centromeres of each duplicated chromosome are aligned
37
What happens in anaphase?
* The centromeres of each duplicated chromosome split and separate * Chromosomes are pulled along the spindle microtubules from the equator to the poles
38
What happens in telophase?
* Chromosomes stretch back out and become indistinct as chromatin * Membrane vesicles form new nuclear membranes around each group of chromosomes at the two poles * The spindle microtubules disperse and the spindle apparatus disappears
39
What is cytogenesis?
When the cell divides in the final stage. | Cleavage occurs by a thin ring of actin filaments which form the contractile ring.
40
How to calculate the mitotic index? NB: a high mitotic index may indicate cancer
Mitotic index = no. of cells in mitosis / total no. of cells
41
What are the 4 nitrogen bases of DNA structure?
Adenine & thymine | Guanine & cytosine
42
What is a telomere?
Like the rest of a chromosome, telomeres are sequences of DNA. They are made of a repeating sequence of six base pairs ``` TA TA AT GC GC GC ```
43
What is telomerase?
An enzyme which adds bases to the end of telomeres, which keeps them from wearing down.
44
What are cyclins?
A family of proteins that stop cells reproducing by activating kinase enzymes (which control cell division) (Can be used in cancer reasearch)
45
What is gene p53?
A human gene located on the 17th chromosome. Can be used to prevent the replication of damaged DNA It does this either by activating proteins involved in DNA repair or by killing the cell by apoptosis.
46
What is endosymbiosis?
The idea that eukaryotic cells are formed from prokaryotic cells by endocytosis See diagram on 23rd October

IB Biology (4 decks)

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