Chromosomes and Mutations

Describe the genome. The whole of the genetic information of an organism

State the relationship between the size of the genome and complexity of the organism. Sizes varies based on organism, not complexity.

Outline the outcomes of the human genome project.

Mapping: Number, location and basic sequence of genes

Screening: Detect sufferers and carriers of genetic diseases

Medicine: Improved treatment for diseases

Ancestry: Understanding of origins, evolution and migratory patterns.

Describe a gene. Length of DNA controlling a heritable characteristic

Describe an allele. Specific form of a gene

Describe a gene mutation. Change in nucleotide sequence in DNA coding for a particular feature.

list 3 causes of mutagens. X Rays, cigarettes, HPV virus

outline the 3 different types of base substitutions.

Silent: Does not alter amino acid sequence

Missense: Causes incorrect amino acid

Nonsense mutations: Creates a premature stop codon

describe frameshift mutation.

caused by insertion or deletion of base

changes reading frame during protein synthesis

every amino is incorrect

describe block mutations.

changes to entire sections of a chromosome

causes large scale changes to DNA

distinguish between somatic and germ line mutations.

somatic cell mutations (mutagens)

- only in body cell

- not in gametes

- cannot be passed onto offspring

germ line mutations (natural)

- in gametes

- can be passed onto offspring

Explain the causes (in detail) and consequences of sickle cell anemia

Explain the causes and consequences of sickle cell anemia (8 marks)

Sickle cell anemia is caused by a missense mutation. In DNA, GAG is turned into GTG. Instead of the GAG codon being made, a GUG codon is. Then instead of glutamic acid being created, valine is. This creates a fibrous hemoglobin protein and sickled red blood cells. Consequently, red blood cells cannot effectively carry oxygen. the person has anemia and feels tired. Sickle cells may form clots.

Describe a karyotype. Number of chromosomes an individual has

Describe a karyogram. Visual profile of all the chromosomes in a cell

arranged into homologous pairs

displayed according to their structural characteristics

Outline how a karyogram is created (4 marks)

harvesting cells

- fetus or adult white blood cells

- halted during metaphase

chromosomes stained and photographed

arranged according to structure

Describe the #1 reason for analyzing a karyogram / application of its use. Test for chromosomal abnormalities (non-disjunction- chromosomes didn’t separate)

Describe ways to obtain fetal cells for a Karyogram (Same as: Describe amniocentesis / Describe chorionic villus sampling).

Amniocentesis

- needle inserted into fetus’ amniotic sac

- sample of amniotic fluid taken

- ~ 16th week of pregnancy, slight chance of miscarriage

Chorionic villus sampling

- tube inserted through cervix

- tiny sample of chorionic villi from placenta

- ~ 11th week of pregnancy, slight chance of miscarriage