3.1 / 3.2 Genes and Chromosomes

Question 1

Non-Disjunction

Answer 1

Chromosomes don’t seperate during cellular division
If it occurs on the 21st, the person has down syndrome

Question 2

Karygram

Display of Down Syndrome too

Answer 2

Shows chromosomes of an organism from largest to smallest in homolous pairs

First 22 are autosomes
23rd is sex determining chromosomes X & Y

Downies:
- 3 chromosomes are displayed on the 21st set (trisomy)

Question 3

Reading the LOCUS positioning

Answer 3

7q3.1

7 = Chromosome number
q = which arm (q is longer)
3 = Region number
1 = band number

Question 4

Cairn’s Technique

6-8 mark question

Answer 4

Process:
1. Cells are grown with radioactive thymine
2. DNA of cells therefore have radioactive thymine
3. Cells are broken, the DNA is collected after cultervating
4. DNA is placed on a slide
5. Slide is placed in radioactive sensitive emulaion
6. Radiation activates Ag+ ions, they turn solid and coat the slide
7. With the silver (Ag+) we can see where the thymine is and therefore see the DNA to measure it

Question 5

Plasmid features

Answer 5

Independent DNA molecule
Circular & double standed
Easily transmitted between bacterium
Some Prokaryotes have plasmids

Question 6

Genes

Answer 6

A heritable factor that onsists of a length of DNA and influences a specific characteristic of an organism
- Can be hormonal or visual characteristics

Specific forms of genes are called alleles (new alleles are formed from mutations)

Question 7

Human Genome

HG Project

Answer 7

Genome:
The totality of genetic info of a cell, organism or organelle

Human Genome Project:
In 2003, it led to many outcomes;
- Showed humans share majority of their sequence, with short nucleotide polymorphisms
- Mapping of genes
- Screening
- Medicine treatments improved
- Ancestry and evolution

Question 8

Diploid Vs Haploid

Answer 8

Diploid:
- Diploid niclei have pairs of mologous chromosomes
- Somatic cells (Body cells)
- 46 chromosomes

Haploid:
- Have one chromosome from each pair
- Gamete cells (sperm & egg)
- 23 chromosomes

Question 9

Sickle cell anaemia

Answer 9

Sickle cell anaemia is an example of a disorder caused by a gene mutation

Causes:
- results from a change to the 6th codon for the beta chain of haemoglobin

Consequence:
- causes insoluble haemoglobin, (insoluble haemoglobin cannot carry oxygen as effectively, causing the individual to feel constantly tired)
- The formation of fibrous haemoglobin strands changes the shape of the red blood cell to a sickle shape