1. Gene Expression

Chapters 11 and 12

2. Prokaryotes

a. 1 circular chromosome

b. Operons:

i. Promotor

ii. Operator

iii. Gene

3. Prokaryote

a. Promotor

i. Non gene region

ii. Binding site for RNA polymerase

iii. Starting point for transcription

iv. May impact more than one gene

4. Prokaryote

a. Operator

i. Non gene region

ii. Binding site for repressor

iii. Repressor blocks transcription

iv. Normal state

b. Genes

i. Protein coding region

ii. Functionally related genes affected by same promotor

5. LAC (lactose) Operon

a. Studied in E. Coli by Jacob and Monod

b. Affects metabolism of Lactose

c. Enzymes spits lactose and change permeability

d. See diagram page 181

6. Normal

a. Regulator gene codes for repressor

b. Repressor binds to operator

c. Operon off

7. Operon function

a. Lactose enters cell and binds to free repressors

b. Lactose removes repressors from operator region

c. Operon on

d. RNA polymerase moves to operon

8. Operon Function

a. Operon produces three enzymes

i. Galactosidase and transacetylase: split lactose

ii. Permease: change permeability

b. When lactose metabolized repressors bind to operator region

c. Operon turned off

9. Eukaryotes

a. Multiple chromosome

b. Each cell has all chromosomes

c. Homeobox, and master control genes

d. Epigenetics

10. Epigentetics (1)

a. Control how genes are used

b. Control tissue type

c. Functional groups attach to control transcription

d. Controls splicing

11. Epigenetics (2)

a. 5% of DNA is active

b. 30% codes for genes

c. 70% regulates genes

d. 22,000 genes, >100,000 proteins

e. Each gene codes more than one protein

12. Histone Code

a. Methyl Group (CH₃): deactivate gene

b. Acetyl Group: Activate gene

c. Phosphate (PO₄): cell division

d. Phosphate on serine: Apoptosis

13. Methylation of cytosine

a. Blocks gene function

b. Linked to disease

c. Linked to environmental effects

d. Passed to offspring

14. Structure in nucleus

a. Euchromatin

i. Coiled DNA

ii. Held by repressive transcription factor

iii. Histone tails methylated

iv. Each cell type methylated differently

b. Promotor

i. Binding site for RNA polymerase

ii. At start of gene

iii. Introns and Exons both transcribed

15. Structure in Nucleus

a. Enhancer

i. Remote from promotor

ii. Transcription factor brings it near promotor

iii. Controls transcription

(1) Increase rate

(2) Increase efficiency

iv. Controls multiple genes

16. Gene control example (HIF-1)

a. Response to change in O₂ supply or demand

b. EPO: more red blood cells

c. VEGF: more blood vessels

d. IGF2 + EPO: inhibit apoptosis

e. GLUT: change O₂ metabolism

17. Actions: Trasncriptions

a. Transcription factor bind to enhancer and promoter

b. Enhancer moved near promotor

c. Enhancer uncoils DNA

d. Transcription factor attaches RNA polymerase to promotor

e. Polymerase transcribes DNA to pre-mRNA

18. Slicing

a. Enzymes remove introns

b. RNA may act as splicing enzyme

c. Epigenetic tags determine exons that stay

d. Exons attached and telomeres added

19. Actions

a. mRNA leaves nucleus and moves to ribosome

b. m RNA translated at ribosome

20. Morphogenesis (development)

a. Zygote: all cells identical

b. Blastula

i. Hollow sphere

ii. 16 to 128 cells

c. Gastrula

i. Sphere folds to form pocket

ii. Precursor of inside

iii. Once pocket formed cells differentiate

21. Genetic Toolbox

a. Control development of organism

b. Control Genes: body areas

c. Master Genes: body Structures

d. Homeobox: form and symmetry

e. Genetic Switches: turn genes on/off

22. Body Sequence

a. Chemical imbalance in embryo

b. One end becomes mouth other anus

c. Proteostomes: first opening mouth

d. Deuterostome: second opening mouth

23. Control Genes

a. Direct formation of imaginal disks

i. Each forms different tissue

ii. Establish direction

b. Produce regulatory proteins

i. Control what something becomes

ii. Turns genes on/off

iii. Shared across species

24. Genetic Switches

a. Coded by DNA between genes

b. Control expression of genes during development

c. Reason only certain genes on in each cell

25. Master Genes

a. Direct formation of specific structures

i. Pax-6: eye development

ii. Distal-less: limb formation

iii. NK2 (tinman): heart formation

iv. Hedgehog: patterning of structures

b. Same genes found in multiple species

i. Ex. Pax-6, tinman, Distal-less

26. Homeobox (HOX)

a. Each 180 bases long (60 amino acids)

b. Regulates patterns of development

i. How many form

ii. Location

iii. Symmetry

iv. Line up on chromosome in order on body

27. HOX Genes

a. Saint-Hilaire

i. Proposed vertebrate body plan upside down insect

(1) Vertebrate spine on top

(2) Insect spine on bottom

ii. Same HOX gene controls formation

28. HOX Genes

a. HOX genes identical across species

i. Mutate fly HOX: structures grow in wrong places

ii. Replace fly HOX with mouse HOX; normal growth

29. HOX Mutations

a. Spread as recessive allele

b. When widespread may become dominant

c. Would appear suddenly as new species

30. Mutations

a. Change in DNA sequence

b. Most are harmful

c. Random variations

31. Mutation Types

a. Germ Cell

i. Do not affect organism

ii. Passed to offspring

b. Somatic Cell

i. Affect organism

ii. Passed by mitosis

32. Mutagens

a. Environmental factor changes DNA

b. UV

c. Radiation

d. Chemicals

33. Chromosome Mutation

a. Change in structure of chromosome (order of genes)

b. Rearrangement

i. Inversion: segment breaks and reverses before joining

ii. Translocation: movement of genes from one chromosome to another

c. Duplication

i. Repetition of a sequence of base pairs (homopolymers)

ii. Spotted vs no spots on pigs

d. Loss: deletion of genes

e. Non-Disjunction

i. Chromosome does not split

ii. Cell has extra copy of chromosome

f. Regulatory Genes

i. Enhancer or transcription factor

ii. Affects when and where genes are activated

iii. Alters development of body parts

iv. Teosinte vs corn

34. Gene (point) Mutation

a. Change in base sequence of DNA

b. Substitution

i. Affects only 1 amino acid

ii. Change in structure of protein

iii. Ex. Black vs yellow lab

c. Frame Shift

i. Add/remove base

ii. Entire code read out of sequence

iii. Changes protein produced

iv. Smooth vs wrinkled peas: 800 pair insertion

35. Sex Determination

a. 2 sex chromosomes

b. Female: both same

c. Male: one of each

d. Male chromosome thought to be female with lost genes

36. Sex Linkage

a. Traits carried on sex chromosomes

b. Generally on female chromosome

c. Red-eye in flies (page 1675-166)