Human Genome Project - Lecture 5

Question 1

Goals of the human genome project

Answer 1

1. Identify all genes in human DNA
2. Determine sequences of DNA base pairs making up human genome
3. Store information in databases
4. Improve data analysis possibilities
5. Transfer tools to private sector
6. Hello address ethical, legal, social issues arise from project

Question 2

How many protein-coding genes humans have ?

Answer 2

~20,000 (less than thought)

Question 3

Human genome base pairs number

Answer 3

Haploid human genome = ~3,200,000,000 base pairs

Question 4

Benefits of HGP

Answer 4

• Personalised medicine (via identifying functions of all genes and their variants)
• Understanding of human evolution

Question 5

Example of potential personalised medicine from HGP

Answer 5

2019: genomic test for breast cancer risk

Question 6

Central dogma - Crick

Answer 6

First suggested by Francis Crick -> DNA makes RNA makes protein
Once a protein, always a protein
RNA and DNA replication also = transfer of info.

Question 7

Revised central dogma

Answer 7

• DNA replicates
• Transcription into RNA
• Translation of this RNA into protein
• RNA then replicates
• Reverse transcription occurs i.e. RNA -> DNA

Question 8

Mendel - father of genetics and inheritance

Answer 8

Used pea experiments to explain and show inheritance

Question 9

Why peas?

Answer 9

• Lots of offspring
• Short generation time
• Self-fertilisation + cross-fertilisation possible
• Contrasting features in lines v noticeable
• Simple

Question 10

Pea colour monohybrid cross 1

Answer 10

Cross based on colour:

Male pollen - green x Female stigma - yellow
F1 = All yellow

Mendel ∴ concluded Yellow = dominant

Question 11

Crossing F1 of the first generation w green

Answer 11

F1 Yellow x Green

Result = Mixture of Green and Yellow in 1:1 ratio.

Mendel ∴ concluded -> Green is recessive (i.e. green trait still there but masked by yellow)

Question 12

Mendel’s first law of inheritance - law of segregation

Answer 12

E.G: If one is yy and one is YY only one Y and one y will be passed on to gamete in formation.
These form F1 generation w mix of alleles depending on dominance etc.

Identical alleles = homozygous
Different alleles = heterozygous

Question 13

Theory of inheritance on chromosomes

Answer 13

Sutton = proposed chromosome theory of inheritance
Morgan = discoverer of sex-linked inheritance

Question 14

Morgan crosses

Answer 14

Crossed normal red-eyed flies with white mutant flies
Conclusion - X chromosome carries genes that are not just sex-determinants (eg eye colour in flies), ∴ genes live on chromosomes.