Genetics and Evolution

Question 1

Evidence for evolution

Answer 1

Fossil remains

Biogeography

Comparative anatomy

Comparative embryology - gill pouches that appear in all vertebrate embryos

Molecular biology - the amino acid sequence in our haemoglobin differs from the rhesus monkey by 5%, mouse by 20%

Question 2

Gregor mendel

Answer 2

Mendel studied inheritance in pea plants

Identified recessive genes

There are alternative forms of genes (alleles)

Each organism has two alleles for a feature (one from each parent)

Each sperm or egg carries one allele

dominant is fully expressed, recessive has no detectable effect

Question 3

Recessive genes

Answer 3

Masked by dominant genes

Even if both parents are recessive, only 25% will be affected

• 25% completely unaffected
• 50% carry

Question 4

phenotype vs genetype

Answer 4

observable characteristic is phenotype

genotype are the genes we have

Question 5

Where are genes found?

Answer 5

In chromosomes

-exist as homologous pairs

Question 6

Two types of genotypes

Answer 6

Homozygous - homologous pairs of chromosomes that carry the same alleles

Heterozygous - homologous chromosomes carry different alleles, a dominant and a recessive

Question 7

what chromosomes do we have?

Answer 7

46

22 pairs of autosomes
1 pair of sex chromosomes

XY male
XX female

Question 8

Meiosis

Answer 8

Creating gamates -

Produces 4 haploid daughter cells
-chromosome number is halved in each daughter cell

Question 9

Mitosis

Answer 9

produces 2 diploid daughter cells

Question 10

Codons

Answer 10

triplets of nucleotide basses

the gene for a protein has a start codon

followed by amino acid codons

stop codon

Question 11

mRNA

Answer 11

forms a copy of the gene’s base sequence in the nucleus

at a ribosome mRNA act as a template for the protein

tRNA transfers the corrects amino acids

Question 12

Nucleotide bases

Answer 12

Adenine
Thymine
Cytosine
Guanine

in Rna U (uracil) replaces T