genetics

Question 1

what is mendelian genetics

Answer 1

traits are inheritable
named after Grefor mendel
performed cross-pollination experiments on peas

Question 2

what dd the pea experiment include

Answer 2

• cross-pollination = true breeding
• then allowed F1 to self-pollinate or cross-polinate to see resutling F2 phenotypes

Question 3

what is a locus

Answer 3

• the location of a gene on a chromosome

Question 4

what is a phenotype

Answer 4

• physical expresson of genotype

Question 5

what is homzygotic vs heterozygotic

Answer 5

• homo = two of same allele for a gene
• hetero = two different alleles for a gene

Question 6

how are alleles masked

Answer 6

if domnant allele is present in coding, this code is used for enxyme production instead

Question 7

what are punnet squares for

Answer 7

• show possible genotypes
• show probability of phenotypes

Question 8

how to do a two trait punnet square

Answer 8

e.g. RrYy -> cross RY, rY, Ry, rY
- each trait will retain a 3:1 ratio in F2

Question 9

what are the laws of medelian inheritance

Answer 9

1. law of dominance
2. law of segregation
3. law of independent assortment

Question 10

what is law of dominance

Answer 10

in cross-fertillisation, dominant trait always masks the recessive

Question 11

what is law of segregation

Answer 11

• two alleles of a gene are separate entities and separate from each other during gametogenesis

Question 12

what is law of independent assortment

Answer 12

• chromosomes distrivuted to gametes individually
• alleles for different traits are also distributed independently if are on different chromosomes
• all combnations of traits are possible

e.g. alleles for colour gene are distributed independently only if on different chromosomes (e.g. yellow allele on one chromosome and green on another could be separated)

Question 13

what s incomplete dominance

Answer 13

• neither allele is wholly dominant
• heterozygous individuals will exhibit a BLENDED phenotype

Question 14

what is codominance

Answer 14

• heterozygous individuals will express both alleles equally
• phenotype of both alleles is present

Question 15

how is blood type determined

Answer 15

• the carbohydrates on red blood cell surface/antigens
• alleles for antigens include IA, IB, i

Question 16

what are the possible genotypes for blood groups

Answer 16

type AB = heterozygous for IA,IB
type A = AA or Ai
type B = BB or Bi
type O = ii

Question 17

what is the dominance pattern for type AB blood

Answer 17

codominant

Question 18

what is different about the Y chromosome

Answer 18

• smaller (less DNA)
• contains Sex Determining Region - initiates sexual differentiation

Question 19

what are autosomal alleles vs sex linked

Answer 19

• alleles located on an autosome
• daughter and sons have equal opporttunity to inherit
• alleles located on sex chromosome
• phenotypes are unequally distributed

Question 20

what is a pedigree

Answer 20

• chart that illustrates inheritance pattern through different generations of a family

Question 21

autosomal dominant

Answer 21

• sexes affected equally (but chance over 50%)
• from mum or dad
• black = have a dominant allele

Question 22

autosomal recessive

Answer 22

• equal chance
• trait only present when two recessives
• trait present if two recessive - 25% chance of inheritance
  -BOTH parents must have a recessive allele
• look for two unaffected parents, but affected young

Question 23

X-linked dominant

Answer 23

• allele on X chrom - by mother or father in daughters
• only 1 dominant X chrom needed
• affected dad and daughter

Question 24

X-linked recessive

Answer 24

• recessive allele on X chrom
• male needs one X-recessive, female needs two for trait to be expressed
• look for unaffected mother, but affected son!! or affected dad, unaffected daughter

Question 25

some facts about mitochondrial DNA

Answer 25

• only from mother
• contains only circular DNA - 37 genes for OP, RNA synthesis, rRNA
• mistakes = sever diseases due to impact on metabolism

Question 26

what is a carrier

Answer 26

• heterozygous but do not display trait