Cellular And Genetic Mechanisms

Question 0

Disadvantages of being single celled

Answer 0

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

Question 1

How does prokaryote bacterial division occur

Answer 1

Binary fission

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

Question 2

Effects of cell size on SA:v ratio

Answer 2

Larger the cell the Sa stays the same

So amount of energy that can enter are limited

Question 3

Chromosome karyogamy

Answer 3

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

Question 4

3 types of centromere location
Top
Middle
Above middle

Answer 4

Telocentric
Metacentric
Acrocentric

Question 5

What is the function of a kinetochore

Answer 5

Where micro tubules attach

Question 6

Non localised kinetocores
Polycentromere
Holocenteomere

Answer 6

Poly- attach to points on chromatid

Holo- attach to any point

Question 7

Centrioles/centrosome

what are they

Answer 7

Duplex

Made up of protein mictotubules which replicate by assembly

Question 8

Plants and animals do not require,…

Answer 8

Centrioles for spindle formation

Question 9

Microtubule organisation center in animals are

Answer 9

Centrosome
Electron dense cloud associated with centrioles
Essential for microtubule production

Question 10

Function of spindle fibres and microtubules

Answer 10

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

Question 11

Structure of microtubules and spindle fibres

Answer 11

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

Question 12

Movement via tubulin

Answer 12

1. Polymerisation

2. Depolymerisation

Question 13

Movement via motor proteins

Answer 13

1. Kinesin usually move to +ve end

2. Dyneins move to -ve end

Question 14

Movement via depolymerisation

Where does it happen and what causes it

Answer 14

At kinetochores spindle poles

Colchicine- low levels promote depolymerisation

Question 15

Astral fibres / spindle pull

What are they attached to

Answer 15

Astra fibres attach to cell membrane regions

Question 16

Prophase 1 meiosis parts

Answer 16

Leptotene
Zygotene
Pachytene 
Diplotene
Diakinesis

Question 17

Leptotene what happens

Answer 17

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

Question 18

Zygotene

Answer 18

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

Question 19

Pachytene

Answer 19

Synapsis complete may remain in this stage for number of days

Question 20

Tetrad

Answer 20

4 chromosomes make up the 2 homologue chromosomes

Question 21

Bilavent

Answer 21

Synapses homologues chromosomes before we can see 4 chromatids

Question 22

Diplotene

Answer 22

Synaptonemal complex dissolves

Homologues still attached to chiasmata

Question 23

Diakinesis

Answer 23

RNA synthesis stops

DNA highly condensed and detached from nuclear envelope

Question 24

Importance of chiasmata

Answer 24

Chromosome orientation Random assortment Act as centromeres

Question 25

Difference in mitosis and meiosis 1

Answer 25

Kinetochores in meiosis only on one side | Important for orientation, independent segregation and correct distribution

Question 26

Difference in mitosis and meiosis 1 | Second answer

Answer 26

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

Question 27

Difference in mitosis and meiosis 1 | Third answer

Answer 27

Meiosis 1 the chiasmata divide | In meiosis 2 and mitosis the centromeres divide

Question 28

Where are the oogonia held at during foetal development

Answer 28

Meiosis 1 initiated in all oogonia until prophase 1 diplotene

Question 29

Fertilisation

Answer 29

Enters second meiotic division | 3 polar bodies and 1 Oocyte at this point

Question 30

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

Answer 30

Female age

Question 31

Key points about female gametes

Answer 31

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

Question 32

Autopolyploid

Answer 32

Multiples of identical genomes

Question 33

Allopolyploid

Answer 33

Multiple genomes of different ancestry

Question 34

2 types of haploidy

Answer 34

Natural- bees | Artificial-

Question 35

Variations in chromosome number 2 types

Answer 35

Aneuploidy- changes in number of a single chromosome | Euploidy- changes in entire chromosome number (genome)

Question 36

Aneuploidy caused by what

Answer 36

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

Question 37

Aneuploidy can occur in

Answer 37

Insects | Male is Xo

Question 38

Euploidy Can occur in

Answer 38

Lizards and fish and plants

Question 39

Odd genomes are not maintained caused by

Answer 39

Non disjunction- of whole genome/failure of cell division | Fertilisation- by more then 1 gamete

Question 40

Autopolyploidy what is it

Answer 40

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

Question 41

Autotriploids AAA are often

Answer 41

Sterile

Question 42

Allopolyploid how does it form

Answer 42

Species AA and species BB combine forming AABB

Question 43

Mendelian rule 1

Answer 43

Always use 2 homozygous parents

Question 44

Advantages of using pure breeds

Answer 44

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

Question 45

Mendels first postulate

Answer 45

For each characteristic gene loci you inherit 2 alleles

Question 46

Second postulate

Answer 46

2 alleles recessive and dominant | One show ones not in heterozygous

Question 47

Complete dominance-mono hybrid inheritance

Answer 47

In complete dominance the recessive allele is not expressed

Question 48

Mendels 3rd postulate

Answer 48

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