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genetic mechanisms > Cellular And Genetic Mechanisms > Flashcards

Cellular And Genetic Mechanisms Flashcards

0
Q

Disadvantages of being single celled

A

Limited life span
No cell replacement
Problems with increase in size
Limited specialisation

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1
Q

How does prokaryote bacterial division occur

A

Binary fission

Single DNA molecule first replicates and attaches each copy to a different part of the cell membrane

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2
Q

Effects of cell size on SA:v ratio

A

Larger the cell the Sa stays the same

So amount of energy that can enter are limited

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3
Q

Chromosome karyogamy

A

Number- constant for species
Size- of chromosomes differ, range is constant for species
Shape- of chromosome differs, pattern constant for species

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4
Q

3 types of centromere location
Top
Middle
Above middle

A

Telocentric
Metacentric
Acrocentric

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5
Q

What is the function of a kinetochore

A

Where micro tubules attach

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6
Q

Non localised kinetocores
Polycentromere
Holocenteomere

A

Poly- attach to points on chromatid

Holo- attach to any point

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7
Q

Centrioles/centrosome

what are they

A

Duplex

Made up of protein mictotubules which replicate by assembly

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8
Q

Plants and animals do not require,…

A

Centrioles for spindle formation

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9
Q

Microtubule organisation center in animals are

A

Centrosome
Electron dense cloud associated with centrioles
Essential for microtubule production

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10
Q

Function of spindle fibres and microtubules

A

Creation of spindles
Metaphase plate alignment
Orientation of chromosome for centromere splitting (independent assortment)
Chromosome movement to poles

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11
Q

Structure of microtubules and spindle fibres

A

Tubulin microtubules
Hollow tubes
2 non identical peptide chains (a and b)

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12
Q

Movement via tubulin

A
  1. Polymerisation

2. Depolymerisation

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13
Q

Movement via motor proteins

A
  1. Kinesin usually move to +ve end

2. Dyneins move to -ve end

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14
Q

Movement via depolymerisation

Where does it happen and what causes it

A

At kinetochores spindle poles

Colchicine- low levels promote depolymerisation

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15
Q

Astral fibres / spindle pull

What are they attached to

A

Astra fibres attach to cell membrane regions

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16
Q

Prophase 1 meiosis parts

A 
Leptotene
Zygotene
Pachytene 
Diplotene
Diakinesis
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17
Q

Leptotene what happens

A

Chromosomes condense
Each end attached to nuclear membrane by plaque
Chromo 1 and 2 find each other while it’s still attached
Attachment plaque causes the pairing

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18
Q

Zygotene

A

Initiation of synopsis formation= synaptonemal complex
Forms synapse
Genetic recob between daughter chromatids require close association
Attachment plaques moe around the membrane and bring them together

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19
Q

Pachytene

A

Synapsis complete may remain in this stage for number of days

20
Q

Tetrad

A

4 chromosomes make up the 2 homologue chromosomes

21
Q

Bilavent

A

Synapses homologues chromosomes before we can see 4 chromatids

22
Q

Diplotene

A

Synaptonemal complex dissolves

Homologues still attached to chiasmata

23
Q

Diakinesis

A

RNA synthesis stops

DNA highly condensed and detached from nuclear envelope

24
Q

Importance of chiasmata

A

Chromosome orientation
Random assortment
Act as centromeres

25
Q

Difference in mitosis and meiosis 1

A

Kinetochores in meiosis only on one side

Important for orientation, independent segregation and correct distribution

26
Q

Difference in mitosis and meiosis 1

Second answer

A

Meiosis 2 independently line up, but unlike mitosis homologues not present as separated in meiosis 1

27
Q

Difference in mitosis and meiosis 1

Third answer

A

Meiosis 1 the chiasmata divide

In meiosis 2 and mitosis the centromeres divide

28
Q

Where are the oogonia held at during foetal development

A

Meiosis 1 initiated in all oogonia until prophase 1 diplotene

29
Q

Fertilisation

A

Enters second meiotic division

3 polar bodies and 1 Oocyte at this point

30
Q

What increases the probability of chromosome abnormality in the foetus in the number of chromosomes

A

Female age

31
Q

Key points about female gametes

A

Not continuous
4 halploid 3 polar
Mitotic multiplication stage
No loss of cytoplasm (inheritance from mother)

32
Q

Autopolyploid

A

Multiples of identical genomes

33
Q

Allopolyploid

A

Multiple genomes of different ancestry

34
Q

2 types of haploidy

A

Natural- bees

Artificial-

35
Q

Variations in chromosome number 2 types

A

Aneuploidy- changes in number of a single chromosome

Euploidy- changes in entire chromosome number (genome)

36
Q

Aneuploidy caused by what

A

Caused by non disjunction of individual chromosome
Laggards usually during meiosis 1 or 2
Forms trisomic or monosomic

37
Q

Aneuploidy can occur in

A

Insects

Male is Xo

38
Q

Euploidy Can occur in

A

Lizards and fish and plants

39
Q

Odd genomes are not maintained caused by

A

Non disjunction- of whole genome/failure of cell division

Fertilisation- by more then 1 gamete

40
Q

Autopolyploidy what is it

A

Doubling of genome
Induced in plants by colchicine
Produced diploid gametes which can self fertilise

41
Q

Autotriploids AAA are often

A

Sterile

42
Q

Allopolyploid how does it form

A

Species AA and species BB combine forming AABB

43
Q

Mendelian rule 1

A

Always use 2 homozygous parents

44
Q

Advantages of using pure breeds

A 
Number of discrete traits
Self fertilisation 
Numerous viable and fertile progeny
Short generation time
Can carry out cross breeding
45
Q

Mendels first postulate

A

For each characteristic gene loci you inherit 2 alleles

46
Q

Second postulate

A

2 alleles recessive and dominant

One show ones not in heterozygous

47
Q

Complete dominance-mono hybrid inheritance

A

In complete dominance the recessive allele is not expressed

48
Q

Mendels 3rd postulate

A

At gamete formation the 2 alleles segregate randomly, one to each pole
Homozygous identical
Heterozygous 50/50 chance to contain 1 allele type

genetic mechanisms (6 decks)

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