Genetics: pedigrees and crosses

Question 1

Gene

Answer 1

Is a segment of DNA that codes different proteins… traits (eg. Eye colour)

Question 2

Alleles

Answer 2

Different forms of a gene(blue or brown eye colour)

Question 3

Dominant

Answer 3

Allele expressed (e.g. Brown eyes)

Question 4

Recessive

Answer 4

Allele not expressed unless both chromosomes contain it (blue eyes)

Question 5

Phenotype

Answer 5

Is the physical characteristic expressed (Brown eyes)

Question 6

Genotype

Answer 6

Is the genetic makeup ( BB or Bb)

Question 7

Homozygous

Answer 7

An organism with two identical alleles (BB or bb)

Question 8

Heterozygous

Answer 8

An organism with two different alleles (Bb)

Question 9

Mendels Pea Plant experiment

Answer 9

Observed yellow as dominant and green as recessive and found ratio of yellow:green was 3:1

Question 10

Law of independent assortment

Answer 10

When two or more pairs of characteristics are considered at one time, each pair shows dominance and segregate independently from the other…. the alleles are not linked together

Question 11

Autosomal dominant inheritance

Answer 11

The child is not affected but both parents are

Question 12

Autosomal recessive inheritance

Answer 12

Both parents are carriers (heterozygous) – they carry the trait but do not express it, even though their offspring does

Question 13

Most dominant

Answer 13

CAPITAL

Question 14

Least dominant

Answer 14

lower case

Question 15

Incomplete dominance

Answer 15

Neither gene is completely dominant over the other
They blend
Horizontal + vertical = diagonal

Question 16

Co-dominance

Answer 16

Occurs when two alleles are expressed at the same time and neither dominates
Horizontal + vertical = checkers

Question 17

Blood groups

Answer 17

Type A
Type B
Type AB
Type O

Question 18

Type A

Answer 18

IaIa or Iai

Question 19

Type B

Answer 19

IbIb or Ibi

Question 20

Type AB

Answer 20

IaIb (universal recipient)

Question 21

Type O

Answer 21

ii (universal donor)

Question 22

Sex linked

Answer 22

X chromosome only carry specific alleles so if the father of a boy is coloured blind that means the fathers mother was a carrier so he got it from the X chromosome and it would therefore not affect his son since the father will only give his son the Y chromosome since the son will get the X from his mother

Question 23

Why are most sex linked traits on the d chromosome and what does this mean

Answer 23

That the X chromosome is bigger and that males are more likely to get this allele

Question 24

Superscript

Answer 24

Like an “exponent” for sex linked or sometimes other chromosomes