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Genes Evo & Dev Y1 > Genes L9 Notes > Flashcards

Genes L9 Notes Flashcards

1
Q

What is population genetics?

A

• Population genetics:

- Study of the gene pool of a population over time

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2
Q

What is molecular genetics?

A

• Molecular genetics:

- Study of the molecular structure & function of genes

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3
Q

Describe factors involved in inheritance & gene function

A

• Inheritance & gene function:

  • Transmission of genes
  • Genotype vs. phenotype
  • Function of genes in organism
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4
Q

What can genetics be applied for? Give examples

A

• Applications of genetics:
- Human genetics
Breast cancer research
- Plant breeding
Genetically modified crops
–>Creation of semi-dwarf (shorter) wheat in India-> less likely blown over -> more likely to grow.
- Analysis of biological processes
Eg. circadian rhythm ->period gene controlling circadian rhythms discovered ->
can modify rhythms of organisms.

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5
Q

What is a gene?

A

• What is a gene?
- DNA molecule
Includes transcribed & non-transcribed regions
Includes exons, introns & gene regulatory regions
- Inherited
- Effects phenotype/physical characteristics of organism
- Located on chromosomes

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6
Q

State the normal amount of haploid & diploid chromosomes in humans

A

• Humans

  • N=23 -> 23 haploid chromosomes
  • 2N=46 -> 46 diploid chromosomes
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7
Q

Distinguish between the two types of cell division

A 
-	Mitosis:
Produce -> 2 genetically identical diploid daughter cells 
1 cell division
Occurs -> All tissues
-	Meiosis:
Produce -> 4 haploid gametes -> from diploid mother cell
2 cell divisions
Occurs -> gonads (ovaries/testes) only.
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8
Q

What is the cell cycle?

A

• Cell cycle:

- Period between -> birth of cell -> division -> 2 daughter cells

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9
Q

Briefly describe Meiosis

A 
•	Meiosis:
-	G2 phase -> S phase cell cycle 
-	Meiosis I:
	Divides pairs of chromosomes
	Reductional division (chromosome no. halved)
	2 haploid (n) daughter cells 
-	Meiosis II:
	Divides sister chromatids
	Equational division
	4 haploid gametes
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10
Q

Describe the process of meiosis I

A

 Meiosis I:
&raquo_space; 2n = 6.
&raquo_space;3 bivalents
-> each -> 4 chromatids.

        Prophase I: 
      Chromosomes condense
      Homologous chromosomes -> synapsis -> (pairing)
      Crossing-over -> genetic material -> non-sister chromatids -> each bivalent
        Metaphase I:
      Homologous chromosome pairs -> line up -> equator of cell. 
        Anaphase I:
      Homologous chromosomes -> separate 
           -> opposite poles of cell 
          -->sister chromatids -> still attached 
         Telophase I: 
      One of original pair -> homologous chromosomes 
          -> each pole of cell
         Cytokinesis I:
      Cells divide -> 2 haploid daughter cells 
          ->Each daughter cell -> chromosome -> 2 chromatids
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11
Q

Describe the process of meiosis II

A

 Meiosis II:
Prophase II:
Chromosomes -> attach -> spindle
Metaphase II:
Individual chromosomes -> line up -> equator
Anaphase II:
Sister chromatids -> separate -> opposite poles of cell.
Telophase II:
Each haploid daughter cell -> 1 each type chromosome.

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12
Q

Describe the process of meiosis

A

 Meiosis I:
&raquo_space; 2n = 6.
&raquo_space;3 bivalents
-> each -> 4 chromatids.

        Prophase I: 
      Chromosomes condense
      Homologous chromosomes -> synapsis -> (pairing)
      Crossing-over -> genetic material -> non-sister chromatids -> each bivalent
        Metaphase I:
      Homologous chromosome pairs -> line up -> equator of cell. 
        Anaphase I:
      Homologous chromosomes -> separate 
           -> opposite poles of cell 
          -->sister chromatids -> still attached 
         Telophase I: 
      One of original pair -> homologous chromosomes 
          -> each pole of cell
         Cytokinesis I:
      Cells divide -> 2 haploid daughter cells 
          ->Each daughter cell -> chromosome -> 2 chromatids

 Meiosis II:
Prophase II:
Chromosomes -> attach -> spindle
Metaphase II:
Individual chromosomes -> line up -> equator
Anaphase II:
Sister chromatids -> separate -> opposite poles of cell.
Telophase II:
Each haploid daughter cell -> 1 each type chromosome.

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13
Q

State the consequences of meiosis

A

Independent assortment

Crossing over

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14
Q

Describe independent assortment

A

 Independent assortment:
- Different arrangement of chromosomes -> lined up at equator of cell -> pulled to diff sides of cell -> metaphase
 Different combinations -> chromosomes -> gametes
2n different gametes -> generated -> independent assortment
->(n=haploid chromosome no.)

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15
Q

Describe crossing over

A
  • Crossing over -> non-sister chromatids -> diff. homologous chromosomes
     New combinations of alleles
  • Recombinant chromatids -> chromatids which have crossed over during meiosis
  • Non-recombinant chromatids -> chromatids which have not crossed over during meiosis
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16
Q

Describe the process of mitosis

A 
•	Mitosis:
-	Prophase:
Chromosomes condense
Mitotic spindle formed -> (composed -> microtubules)
Nuclear envelope -> breaks down 
Chromosomes attach -> mitotic spindle 
-	Metapahse:
Chromsomes line up -> equator of cell
Sister chromatids -> attached -> opposite poles -> mitotic spindle
-	Anaphase:
Microtubules contract -> breaks bonds between sister chromatids
Sister chromatids pulled -> opposite poles of cell
-	Telophase:
Chromosomes spread out 
Nuclear envelope reforms
-	Cytokinesis
17
Q

What is the centromere?

A

• Centromere
Assembles kinetochore
—>Attaches to microtubules

18
Q

What is the telomere?

A

• Telomere

Stabilise ends of chromosomes

19
Q

What are recombinant chromatids?

A
  • Recombinant chromatids -> chromatids which have crossed over during meiosis
20
Q

What are non-recombinant chromatids?

A
  • Non-recombinant chromatids -> chromatids which have not crossed over during meiosis
21
Q

What are the characteristics of a monohybrid cross?

A 
•	Monohybrid crosses:
	1 gene loci 
2 alleles of gene 
Eg. Gene -> eye colour 
     -> Blue eyes (b) / brown eyes (B)
>>Inheritance -> 1 trait
22
Q

What are the characteristics of a dihybrid cross?

A 
•	Di-hibrid crosses:
-	2 different gene loci 
 2 alleles of each gene. 
Eg. Gene -> eye colour 
       -> Blue eyes (b) / brown eyes (B)
       Gene -> eye size 
       -> Small eyes (w) / Wide eyes (W)
>>Inheritance -> 2 traits
23
Q

Phenotypic ratio of F2 generation offspring in monohybrid cross

A

3:1

24
Q

Phenotypic ratio of F2 generation offspring in dihybrid cross

A

9:3:3:1

25
Q

Offspring Genotypic % ratio -> homozygous parents (RR x rr)

A

100% heterozygous

-> All -> same genotype (Rr)

26
Q

% of offspring genotypes & phenotypes -> homozygous parents
(BB x bb)

A

100% Bb genotype

100% Brown eyes phenotype

27
Q

% of offspring genotypes & phenotypes -> homozygous parents
(BBpp x bbPP)

A

100% BbPp genotype

100% Brown eyes & Tanned skin genotype

28
Q

What would the phenotypic & genotypic results of offspring be for these combinations of genotype. Explain why this is the case.
(BBpp x bbPP)
(BBPP) x (bbpp)

A

Phenotype:
Both combinations -> 100% BbPp offspring
Both combinations -> heterozygous offspring
Both combinations -> Same physical characteristics

29
Q

Homozygous mono & di-hybrid crosses will always result in
-> 100% heterozygous offspring
-> 100% offspring of same gentotype & phenotype
Eg. RR x rr–> 100% Rr
Eg. RRbb x rrBB -> 100% RrBb
RRBB x rrbb -> 100% RrBb

A

Homozygous mono & di-hybrid crosses will always result in
-> 100% heterozygous offspring
-> 100% offspring of same gentotype & phenotype
Eg. RR x rr–> 100% Rr
Eg. RRbb x rrBB -> 100% RrBb
RRBB x rrbb -> 100% RrBb

30
Q

What is the multiplication rule -> Mendel’s theory of inheritance

A

> > Rules:
Multiplication rule:
- Random fertilisation
- Independent events -> Probability -> event -> occurs in specific way
Eg. Heterozygote -> Rr
&raquo_space;P(Heterozygote) = P(R) x P(r)

31
Q

What is the addition rule -> Mendel’s theory of inheritance

A

Addition rule:
- Random fertilisation
- Mutual event -> Probability -> event -> can occur in more than one way
Eg. Dominant phenotype -> RR / Rr
&raquo_space; P(Dominant phenotype) = P(RR) + P(Rr)

32
Q

What is Mendel’s 1st law?

A

• Mendel’s 1st law:
Principle of Segregation:
Alleles of single gene equally segregate -> gametes

33
Q

What is Mendel’s 2nd law?

A

• Mendel’s 2nd law:
Principle of independent assortment
Alleles of different genes segregate independently into gametes

34
Q

Outline the genotypes and phenotypes of offspring from generations 1 & 2 as a result of homozygous monohybrid cross

A

• Mating -> two homozygous individuals -> one dominant & one recessive
 1st generation:
YY & yy
4 x Yy genotypes -> 100% heterozygous Yy
F1 (First filial) offspring -> same genotype (Yy) & phenotype (yellow)
F1 -> first-selfed / self fertilised
 2nd generation:
Yy & Yy
1 x YY ; 2 x Yy ; 1 x yy
F2 (Second filial) offspring -> 3 different genotypes -> 1:2:1
-> 2 different phenotypes -> 3:1
&raquo_space;> 3:1 phenotypic ratio -> 2 alleles -> same gene.

35
Q

Outline the genotypes and phenotypes of offspring from generations 1 & 2 as a result of homozygous dihybrid cross

A

• Mating -> two homozygous individuals -> one dominant & one recessive
 1st generation:
 RRyy & rrYY
 100% RrYy genotype
 100% Round, yellow phenotype
F1 (First filial) offspring -> same genotype (RrYy) & phenotype (Right-handed & yellow)
2nd generation:
 RrYy x RrYy
» 9:3:3:1 phenotypic ratio
 9 Round yellow / 3 round green / 3 wrinkled yellow / 1 wrinkled green

36
Q

Outline the genotypes and phenotypes of offspring from generations 1 & 2 as a result of homozygous monohybrid cross & homozygous dihybrid cross

A 
Mono:
 1st generation: 
    YY & yy  
4 x Yy genotypes -> 100% heterozygous Yy genotype
                             -> 100% yellow phenotype
	2nd generation:
     Yy & Yy
-> 2 different phenotypes
    > 3:1 phenotypic ratio 
    Di:
1st generation: 
 RRyy & rrYY
	100% Heterozygous RrYy genotype 
	100% Round, yellow phenotype 
 2nd generation:
	RrYy x RrYy
-> 4 phenotypes
>> 9:3:3:1 phenotypic ratio

Genes Evo & Dev Y1 (23 decks)

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