3.1 and 3.2

Question 1

What is the cause of sickle cell anemia?

Answer 1

Caused by a base substitution mutation, from GAG to GUG in the mRNA, which will be a mutation in a subunit of haemoglobin. This base change, is an amino acid change from Glutamic acid to Valine, which distorts the structure of hemoglobin, which causes a shape change of the red blood cells.

Question 2

How does sickle cell anemia affect people?

Answer 2

The sickle- shaped blood cells block blood flow and can’t transport enough oxygen, so it leads to fatigue. The low oxygen concentration seriously affects the shape of Hbs. Homozygous causes severe anemia, and heterozygoes has less effect. It provides protection against malaria though.

Question 3

How is the DNA in prokaryotes?

Answer 3

circular, one chromosome, naked, in the nucleoid, no nucleus

Question 4

What are plasmids?

Answer 4

Small circular DNA molecules that only contain some genes, and are capable of self-replication. During bacterial conjucation, one pili gets really long and connects to another bacterium, and a copy of the plasmid is transferred, so changes can occur within the same generation.

Question 5

How is the DNA in Eukaryotes organised?

Answer 5

DNa is wrapped around 8 histones = nucleosome, the nucleosomes together are called chromatin & all the chromatin is a chromosome. The chromatin only supercoils during cell division though.

Question 6

Homologous chromosome pairs carry the same sequence of genes, but possibly different alleles. True or false?

Answer 6

Trueeeeee

Question 7

Which chromosome determines sex? What is the name of all the other chromosomes?

Answer 7

Heterosomes. The rest are autosomes.

Question 8

What is a karyogram?

Answer 8

A graphic arrangement of chromosomes

Question 9

Describe Cairn’s technique for measuring the length of DNA.

Answer 9

Cells are grown in radioactive thymidine, so that it incorporates itself in the DNA. Then the chromosomes are isolated from the cells and fixed onto a slide, which is put in to a radioactive emulsion containing silver-bromide. The radiation converts Ag+ to Ag, and when the AgBr is washed away, the Ag remains in place and with a photographic film, it can be seen.

Question 10

Which species have a higher diploid chromosome number than humans? Which have the lowest?

Answer 10

dogs, chicken, monkeys higher,
plants and insects have the lowest