B19

Question 1

Mutagen

Answer 1

Increases rate of spontaneous mutations.
Chemical (deaminating agents).
Physical (ionizing radiation).
Biological (alkalines, base analogs, viruses).

Question 2

Gene Expression

Answer 2

Process by which info from gene used to synthesise gene products. (regulating the synthesis of products).
1. Transcriptional (genes on/off).
2. Post-transcriptional (mRNA modified, regulates protein type).
3. Translational (stopped/started).
4. Post-translational (folding proteins into tertiary structure - changes function).

Question 3

Transcriptional Control

Answer 3

Chromatin remodelling and Lac Operon.

Question 4

Chromatin Remodelling

Answer 4

DNA = -ve. Histones = +ve. = Chromatin.
HETEROCHROMATIN = tightly wound, cell div., NO transcription.
EUCHROMATIN = loosley wound, interphase, freely transcribed.
Add acetyl group makes histones more -ve, so DNA coils less tight, allowing transcription (methyl groups do the opposite).

Question 5

Epigenetics

Answer 5

The control of gene expression in the modification of DNA.

Question 6

Operon

Answer 6

Group of genes transcribed at the same time (usually control biochemical processes).
Only in PROKARYOTES.
e.g. Lac Operon in E.Coli. (Gluc needed for respiration, if no glucose, lactose used instead, hydrolysed to form glucose/galactose by beta-galactosidase).

Question 7

Body Plans

Answer 7

General structure of an organism (head/abdomen).

Question 8

Morphogenesis

Answer 8

Regulation of pattern of anatomical development. Causes cell, tissue or organism to develop shape.

Question 9

Homeobox Gene

Answer 9

Control of the position of structures. Morphogenesis controlled by the Master Homeobox Gene (180 base pairs long).

Question 10

Apoptosis

Answer 10

aka Programmed Cell Death or Altruistic Cell Death.
1. Defence against pathogens or dangerous damaged cells.
2. Part of normal developmental process for organisms e.g. removing skin between fingers.

Question 11

Gene Mutation

Answer 11

Change in nucleotide seq.
1. SILENT (nonsense, missense).
2. DELETION (frameshift).
3. INSERTION (frameshift).

Question 12

Chromosome Mutation

Answer 12

Changes to part of or 1 chromosome.
1. DELETION (section breaks off).
2. DUPLICATION (of section).
3. INVERSION (section breaks off, reversed, joins back on to chromosome).
4. TRANSLOCATION (section breaks + joins another non-homologous chromosome).