Biology - inheritance

Question 1

gene

Answer 1

short sequences of dna on chromosomes which code for a protein

Question 2

allele

Answer 2

different variations of genes

Question 3

dominant

Answer 3

only one dominant allele is needed to determine the phenotype

Question 4

recessive

Answer 4

only determines the phenotype if there are two copies of it

Question 5

heterozygous

Answer 5

if an individual has two different alleles of that gene

Question 6

homozygous

Answer 6

if an individual has two alleles of a gene that are the same

Question 7

genotype

Answer 7

combination of alleles

Question 8

phenotype

Answer 8

visible characteristics as a result of the alleles

Question 9

chromosomes

Answer 9

condensed strands of dna
all our genetic material is held in 23 pairs of chromosomes

Question 10

genetic diagrams

Answer 10

punnett squares
family trees

Question 11

polydactyly

Answer 11

• caused by dominant allele
• extra fingers and toes (digits)
• 50% chance of inheriting polydactyly given one parent is heterozygous and the other doesnt have polydactyly

Question 12

cystic fibrosis

Answer 12

• caused by recessive allele
• involves problems such as difficult breathing and digestive problems due to thick, sticky mucus produced which block passageways around lungs and pancreas
• sufferer is homozygous recessive
• 1 in 25 carry the gene for cystic fibrosis

Question 13

what are family pedigree diagrams

Answer 13

family tree
shaded / half-shaded / unshaded symbolize homo/heterozygous, usually shaded means they carry the gene