lecture 3 Flashcards
1
Q
Mendell
A
- basic principle in heredity of breeding garden peas
2
Q
Experiment of peas
A
- pea plants available in many variets with distinct heritable features (different traits)
- strictly control whihc plants mated
- male a female organs for each plant
- true breeding = plants self pollinate (offspring with same trait)
- hybridisation (cross pollination)
- P generation, hybrid F1 generation
- self pollinate for F2
3
Q
Law of segregation
A
- two alleles for character separated during formation of gametes
- blending model correct then F1 self-fertilise, F2 generation include purple/white plants
- white absent in F1
- ratio 1 white to 3 purple F2
- purple dominant, white recessive
4
Q
Mendell hypothesis
A
- alternative versions of genes account for variations inherited
- each character, an organism inherits two alleles (1 from each parent)
- if alleles at locus differ, one dominant allele determines organisms appearance. Other recessive allele no noticable effect on appearance
- law of segregation, two alleles for a heritable character separate and segregate during gamete production and end up in different gemetes
5
Q
MH 1
A
- two colour versions of flower in peas (purple white)
- alternate versions called alleles
- gene resides at specific locus on specific chromosome
- DNA at locus can vary sequence nucleotides
6
Q
MH 2
A
- diploid inherited one set of chromosomes from each parent
- diploid homologous pair (two copies of each gene)
- homologous loci may be identical
- or two alleles may differ
7
Q
MH 3
A
- in flower colour eg. F1 plants inherited purple allele from on parent and white allele from other
- purple is dominant therefore flower is purple
8
Q
MH 4
A
- segregation of alleles correspond to distribution of homologous chromosomes to different gemetes in meiosis
- two identical alleles = allele present as single copy in all gemetes
- different alleles = 50% gametes recieved each type of allele
9
Q
terminology
A
- homozygous = identical alleles
- heterozygous = different alleles
- phenotype = organism’s traits
- genotype = genetic makeup (two organisms may have same phenotype but different genotype: hetero/homozygous)
10
Q
law of independent assortment
A
- each pairof elleles segregate independently into gametes
- for experiment F1 progeny produced monohybrids (heterozygous for 1 character)
- dihybrid cross (inheritence of seed colour/shape); - alleles segregate independently due to phenotypes (yellow/green/wrinkled) not being just yellow (implying staying together)
- 4 classes of alleles from each ova and sperm = 16 probable ways
11
Q
Laws of probability
A
- laws of segregation reflect probability
- multiplication rule (multiply iindividual probabilities); also applies for dihybrid crosses
- rule of addition (sum of separate probabilities)
12
Q
particulate behavious of genes
A
- can predict probability having specific genotype/phenotype but not for any particular seed
13
Q
inheritance patterns v
A
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