Genetics, Variation And Relationships Between Organisms

Question 1

What is a gene?

Answer 1

It is a section of DNA that codes for a particular polypeptide or protein.

Question 2

What is the position of a gene called?

Answer 2

A locus

Question 3

What is the triplet code that always starts a sequence?

Answer 3

Methionine

Question 4

How many stop codons are there and what do they do?

Answer 4

There are 3 stop codons. They don’t code for amino acids and mark the end of the chain.

Question 5

What does it mean when we say genetic code is universal?

Answer 5

It means that the same sequence of 3 bases will always code for the same amino acid.

Question 6

What does it mean when we say genetic code is non-overlapping?

Answer 6

Each DNA base is only read once in the sequence.

Question 7

What does it mean when we say genetic code is degenerate?

Answer 7

Most amino acids have more than one triplet code.

Question 8

What are mini satellites?

Answer 8

They are large amounts of DNA that do not code for any proteins or polypeptides, found between genes.

Question 9

What are introns?

Answer 9

They are areas of non-coding DNA within a gene.

Question 10

What is the coding DNA in a gene called?

Answer 10

Exons

Question 11

Which type of organisms can have mini satellites and introns?

Answer 11

Eukaryotic organisms

Question 12

What is a genome?

Answer 12

All the genes required to build a functional organism.

Question 13

What is an allele?

Answer 13

It is the different form of a gene.

Question 14

What is the structure of an RNA molecule?

Answer 14

Ribose sugar attached to a phosphate and an organic base (AUCG)
and a phosphate.
Made in a condensation reactions

Question 15

What is the order of taxon?

Answer 15

Domain (dont)
Kingdom (kill)
Phylum (Phil)
Class (cause)
Order (our)
Family (friends)
Genus (get)
Species (sad)

Question 16

Define species.

Answer 16

A group of similar organisms able to reproduce and produce fertile offspring.

Question 17

How do we name organisms?

Answer 17

(in italics) Genus name + species name

Question 18

Define hierarchal system.

Answer 18

Smaller groups contained within larger groups with no overlap.

Question 19

What is phylogenetics?

Answer 19

The study of patterns of evolutionary history.

Question 20

All organisms evolved from…

Answer 20

… shared common ancestors.

Question 21

Define natural selection.

Answer 21

The process by which organisms that are better adapted to their environment survive and reproduce in greater numbers, resulting in the increase of the frequency of advantageous alleles within the population.

Question 22

How does natural selection occur?

Answer 22

1. Selection pressures within the environment change.
2. Variation caused by mutation leads to new alleles of certain genes.
3. Better adapted individuals are more likely to survive and reproduce.
4. Adaptations can be anatomical (related to anatomy), physiological (related to normal function of body systems) or behavioural (the organisms behaviour in the environment)
5. These organisms are more likely to pass on their advantageous allele.
6. The allele is inherited by the next generation.
7. Over many generations, the advantageous allele frequency increases
8. Selection pressure determines the spread of an allele within a gene pool.

Question 23

What are the different types of adaptation?

Answer 23

• Anatomical (related to anatomy)
• Physiological (related to normal function of body systems)
• Behavioural (the organisms behaviour in the environment)

Question 24

What is stabilising selection?

Answer 24

It occurs in all populations where the environment is stable. There is selective pressure at both ends of the distribution so favours the average.
This type tends to eliminate extremes, reduces variability (the size of the range within the population) and reduces the opportunity for evolutionary change.

Question 25

How does transcription work?

Answer 25

Helicase breaks down hydrogen bonds.
There is only one DNA strand that acts as a template.
The RNA nucleotides are attracted to the exposed DNA bases according to the base pairing rule.
DNA polymerase joins the RNA molecules together
Pre-mRNA spliced to remove introns.

Question 27

How does translation work?

Answer 27

Ribosomes bind with mRNA
Ribosomes moves to start codon (AUG)
tRNA carries a specific amino acid
Anticodon on the tRNA is complementary to mRNA codon
Ribosome moves to next codon
Amino acids join using energy from ATP to form a polypeptide (as peptide bonds are made)
Ribosome releases the mRNA once stop codon is reached.