Molecular Homology (11.1)

Question 1

State what evidence was used prior to molecular techniques to determine relatedness between species

Answer 1

Morphological and functional similarities

Question 2

Describe homologous features

Answer 2

Features that are similar because the organisms share a common ancestor

Question 3

Describe analogous feautres

Answer 3

Features that have similar structures and functions bu t have evolved independently and do not share a recent common ancestor

Question 4

State what analogous features are a result of

Answer 4

Convergent evolution

Question 5

State what homologous features are retain through

Answer 5

Divergent evolution

Question 6

Describe divergent evolution

Answer 6

The evolution of two or more different species from a common ancestral species

Question 7

Describe convergent evolution

Answer 7

The evolution of similar features in unrelated groups of organisms (which do not share a common ancestors)

Question 8

State what 2 things similar features can result from

Answer 8

1. Shared ancestry (homologous)

2. Independent evolutionary paths (analogous)

Question 9

State what a similar set of what three things provides evidence of a common ancestor

Answer 9

1. Proteins
2. Chromosomes
3. DNA sequences

Question 10

State what all organisms on Earth once shared

Answer 10

A common ancestor

Question 11

State what would occur if two populations become isolated from each other

Answer 11

They will accumulate different mutations in their DNA

Question 12

State what occurs to the sequences of nucleotides in the DNA of organisms in isolated populations

Answer 12

It becomes more different and what was once similar DNA gradually diverges

Question 13

State what the more mutations that accumulate in DNA sequences between two species is evidence of

Answer 13

The greater the time that has passed since the two species diverged from their common ancestor

Question 14

State what changes in nucleotide sequences are caused by

Answer 14

Mutations

Question 15

State what may occur when a cell copies its’ DNA

Answer 15

Errors may occur

Question 16

State what generally occurs to errors that are made by cell DNA is copies

Answer 16

Repair of these errors prior to mitosis

Question 17

State what occurs occasionally when errors in copied DNA are not repaired prior to mitosis

Answer 17

Errors become a permanent part of the genome

Question 18

State what errors in copied DNA that become a permanent part of the genome are referred to as

Answer 18

Mutations

Question 19

State what will occur if mutations occur within the germ line cells of an organisms

Answer 19

The mutations will be passed on to the next generation

Question 20

State whether or not mutations occur regularly

Answer 20

Yes. Mutations occur regularly as a species evolves

Question 21

State an alternative term to describe the regular occurrence of mutations in the germline cells of an organism

Answer 21

‘molecular clockwork’

Question 22

State what occurs in relation to mutations as time passes

Answer 22

Mutations accumulate in genetic differentiation and divergence of species

Question 23

State what will occur when two species diverge from a common ancestor

Answer 23

They accumulate different mutations in their DNA

Question 24

State what occurs when two species accumulate different mutations in their DNA

Answer 24

They start accumulating differences in the amino acid sequences of their proteins

Question 25

Describe the trend that follows an increase in time passed and differences in the amino acid sequences of species

Answer 25

The greater the time that has passed, the more differences there are between their amino acid sequences of species which have diverged from a common ancestor

Question 26

State whether or not point mutations, in the DNA sequences always cause a difference in the amino acid sequence

Answer 26

No. Point mutations in the DNA sequence may not cause a difference in the amino acid sequence.

Question 27

State why point mutations in the DNA sequence may not always cause a difference in the amino acid sequence

Answer 27

The genetic code is degenerate

Question 28

State whether or not a point mutation that leads to a change in an amino acid may lead to a change in phenotype

Answer 28

No. Changes in the amino acid structure do not always cause a change in phenotypical structure.

Question 29

State what the effect an amino acid substitution has on the function and structure of a protein is dependent on

Answer 29

How biochemically similar the substituted amino acid is to the original amino acid in properties such as size, hydrophobicity and charge

Question 30

State what an amino acid when it is substituted for another with biochemically similar properties is called

Answer 30

A conservative substitution

Question 31

Describe conservative substitution

Answer 31

A change in the nucleotide sequence of DNA or RNA that leads to the replacement of one amino acid with a functionally similar one

Question 32

State whether or not a conservative substitution causes a change in the protein

Answer 32

A conservative substitution does not cause a change in the protein produced

Question 33

Describe a semi-conservative substitution

Answer 33

A replacement of an amino acid with one that has a similar shape but different biochemical properties

Question 34

State what a semi-conservative substitution leads to

Answer 34

Possible change in protein structure and function

Question 35

Describe a non-conservative substitution

Answer 35

A substitution of one amino acid with another that has different biochemical properties

Question 36

State what a non-conservative substitution leads to

Answer 36

Major changes in protein structure and function

Question 37

State what the order of nucleotides in the DNA indicates

Answer 37

Evolutionary relationship between species

Question 38

State whether or not it is more accurate to determine the evolutionary relationship between species by analysing the order of nucleotides in DNA

Answer 38

Yes. Compared to the amino acid sequence.

Question 39

Describe homology

Answer 39

Similarity in structure between parts of different organisms due to evolutionary differentiation from a corresponding part in a common ancestor