lecture 6 the nature of biological variation

Question 1

what is macro evolution

Answer 1

evolutionary change, over long periods of time, on a large scale

Question 2

what are examples of macroevolution

Answer 2

origin of new taxonomic groups
evolutionary trends, e.g. convergence
new kinds of organisms penetrating new habitats, e.g. adaptive radiation
mass extinctions

Question 3

what is microevolution

Answer 3

It is the basis of natural selection, whereby a population progressively adapts to its environment
Change at/below species level

Question 4

what do we mean by population

Answer 4

A group of individuals of the same species living in a particular geographical location

Question 5

what are some examples of microevolution

Answer 5

natural selection

variation based on location

Question 6

genotype

Answer 6

– the genetic ‘makeup’ of an individual

Question 7

phenotype

Answer 7

observable characteristics 
(genotype and environment)

Question 8

chromosomes

Answer 8

gene carrying’ structures found in nucleus

Question 9

what are homologous chromosomes

Answer 9

chromosomes that carry genes controlling the same characteristics
Most eukaryotes have pairs of homologous chromosomes; one set from each parent

Question 10

what are genes made of

Answer 10

DNA

Question 11

what are alleles

Answer 11

alternative forms of a gene = variation in the DNA sequence for a given gene

Question 12

how many homologous pairs do humans have

Answer 12

23

Question 13

what does it mean to be homozygous

Answer 13

the homologous pair have the same allele for the gene

Question 14

what does it mean to be heterozygous

Answer 14

the homologous pair has different alleles for the same gene

Question 15

alleles can be B or b

Answer 15

dominant or submissive

Question 16

how does three meters of dna fit into every cell???????

Answer 16

super coiling

Question 17

what is karyotyping

Answer 17

pair and order chromosomes

Question 18

how does asexual reproduction happen

Answer 18

mitosis

Question 19

what is mitosis

Answer 19

splitting of a parent cell into two daughter cells that are genetically identical to each other and the parent

Question 20

4 ways asexual reproduction can occur

Answer 20

Fission
Budding
Parthenogenesis
vegetative reproduction and fragmentation

Question 21

how much genetic variation occurs with asexual reproduction

Answer 21

little

Question 22

what is binary fission

Answer 22

one cell divides into two cells of similar size with the same genetic material

Question 23

what is budding

Answer 23

new individuals spilt off from parent cell, genetically identical but smaller

Question 24

what is parthenogenesis

Answer 24

development of unfertilised egg

obligate in some species facultative in other species

Question 25

what is vegetative reproduction

Answer 25

A form of asexual reproduction in plants, in which multicellular structures become detached from the parent plant and develop into new individuals that are genetically identical to the parent plant.

Question 26

what is fragmentation

Answer 26

A form of asexual reproduction wherein a parent organism breaks into fragments, each capable of growing independently into a new organism.

Question 27

what happens in sexual reproduction

Answer 27

haploid gametes formed by meiosis fure to form a diploid zygote

Question 28

what meiosis

Answer 28

one cell splits into 4 daughter cells with different dna and only one half of a each homologous chromosome

Question 29

how does meiosis drive variation for evolution

Answer 29

independant assortment exchange of DNA between homologous chromosomes random fertilisation

Question 30

what is independant assortment of chromosomes

Answer 30

how the chromosomes line up in the cell each time before being seperated in meiosis

Question 31

what is exchange of DNA between homologous chromosomes

Answer 31

by crossing over in meiosis wherein a pair of homologous chromosomes may swap sections in DNA

Question 32

what is random fertilisation

Answer 32

Zygotes contain chromosomes from two parents Different alleles from each parent which are chosen randomly from loadsssss of combinations each zygote has 1 of 70 trillion possible diploid combinations + variation from crossing over

Question 33

advantages of sexual evolution

Answer 33

in a stable environment the best genotype is perpetuated | uses less energy and is quicker

Question 34

advantages of sexual reproduction

Answer 34

produces a lot of variation- new combinations may work better than older ones in a changing environment veriation may promote overall survival

Question 35

how are different alleles generated?

Answer 35

chromosomal mutations

Question 36

multi level variation, what are the levels

Answer 36

chromosomal, alleles, single point mutations, single nucleotide polymorphisms

Question 37

how do single nucleotide polymorphisms contribute to variation

Answer 37

hey can change an amino acid, therfore a protien, therefore a function

Question 38

what is polypolidy

Answer 38

multiple sets of chromosomes Occurs at cell/ tissue/ whole organism level Common in plants (~50-70% angiosperms) Liver cells are often polyploid

Question 39

what are the two types of polypolidy

Answer 39

autopolyploidy and allopolyploidy

Question 40

what is Autopolyploidy

Answer 40

error in mieosis/mitosis - Single species genome duplication (single parent) e.g., Chromosome number increases from a diploid to a tetraploid (4 copies per cell).

Question 41

what is allopolyploidy

Answer 41

error in mieosis/mitosis- Two different, related species interbreed, hybridise, then chromosome number doubles- not common

Question 42

what does polyploidy result in

Answer 42

reproductive isolation

Question 43

is there substantial variation within species

Answer 43

yes

Question 44

most DNA is non coding and was thought to be

Answer 44

silent DNA and not important

Question 45

while it isn't subject to natural selection, non coding DNA...

Answer 45

it will change by mutation and genetic drift | and it can have a functional role which affects how genes are expressed

Question 46

what is the normal genotype for haemaglobin

Answer 46

HnHn

Question 47

what happens to red blood cells if there is a single point mutation and HsHs occurs or HnHs

Answer 47

HsHs is fatal | HnHs can lead normal lives with blood transfusions

Question 48

how does anaemia show co dominance

Answer 48

normal allele is not dominant over sickle allele they both are expressed

Question 49

sickle cell heterozygotes are better adapted in

Answer 49

areas where malaria occurs

Question 50

why is this "sickle cell heterozygotes are better adapted in areas where malaria occurs

Answer 50

Selection pressure from malaria maintains lethal sickle cell allele in the gene pool of the population