Topic 3

Question 1

Protein transport - process

Answer 1

1. TRANSCRIPTION (dna-mrna)
2. mRNA LEAVES nucleus
3. protein made on ribosomes enter rough ER and moves through assuming 3D SHAPE
4. VESICALS PINCHED off rough ER contain protein and FUSE to form flattened sacs of GOLGI APPARATUS
5. proteins MODIFIED - vesicles pinch off and FUSE w/ CSM

Question 2

Fertilisation - process

Answer 2

1. chemicals released by ovum attract sperm
2. egg and sperm meet - ACROSOME REACTION - breaks down zona pellucida
3. egg and sperm membrane touch
4. CHARGE in OVUM REVERSED - block entry of more s
5. CORTICAL REACTION - hardens zp
6. egg and sperm fuse

Question 3

Meiosis - process

Answer 3

1. replicate
2. random assortment
3. crossing over
4. split x2

Question 4

Mitosis - INTERPHASE

Answer 4

• G1/2 New organelles, membranes, dna, proteins formed

- S dna synthesis

Question 5

Mitosis - process

Answer 5

1. PROPHASE - chromosomes condense, nuclear envelope breaks down, spindle forms
2. METAPHASE - centromeres attach to spindle, chromosomes line up in the middle
3. ANAPHASE - spindle fibres shorten, pulling chromatids towards poles
4. TELOPHASE - chromosomes unravel and nuclear envelope reforms around each set of chromosomes
5. CYTOKENESIS - cytoplasm divides

Question 6

Pluripotent

Answer 6

can form most cell types - inner cell mass

*isolated from spare embryos

Question 7

Multipotent

Answer 7

always able to develop into other cell types

Question 8

Totipotent

Answer 8

can develop into any cell type

*most cells in plants

Question 9

Therapeutic Cloning - process

Answer 9

1. nucleus from diploid body cell fused w/ empty egg cell (SOMATIC CELL NUCLEAR TRANSFER
2. cell STIMULATED to divide
3. blastocyst develops, stem cells isolated
4. stem cells develop into cells and tissues and is genetically identical to donor of original diploid cell

Question 10

Epigenetics - Mice phenotype - diet

Answer 10

1. two mice
   - one brown and healthy - agouti gene not methylated
   - one yellow and fat - agouti gene methylated (not expressed)
2. agouti protein binds to MSH receptors in skin and prevents production of dark pigment
3. mice have similar receptor in brain for feeding - blocked receptors lead to overeating

If fat mouse fed methyl rich diet her young will be normal

Question 11

Epigenetics - Mice - stress

Answer 11

1. two mice
   - Good mother = calm, licks and grooms pups a lot
   - Bad mother = nervous, doesn’t L&G
2. offspring grew to be similar to mother
3. however, if pups swapped - acted as foster mum

In pups w/ bad mother GR gene heavily methylated

• stress hormone released
• GR gene not expressed - can’t produce receptor protein for calming
• stress remins high - low LG