3.1 Genes

Question 1

What is DNA also known for?

Answer 1

Being the genetic blueprint

Question 2

What does DNA code for and determine?

Answer 2

The characteristics of an organism

Question 3

What type of features does DNA code for?

Answer 3

Physical
Behavioural
Physiological

Question 4

What is DNA packaged and organised into?

Answer 4

Discrete structures called chromosomes

Question 5

What is a gene?

Answer 5

The sequence of DNA that encodes for a specific trait

Question 6

Is a specific trait influenced always by only one gene?

Answer 6

No sometimes it is influenced by multiple genes

Question 7

What is the locus?

Answer 7

The position of a gene on a particular locus

Question 8

What is the plural of locus?

Answer 8

Loci

Question 9

What are alleles?

Answer 9

Alternative forms of a gene that code for the different variations of a specific trait

Question 10

As alleles are alternative forms of the one gene, what do they possess?

Answer 10

Very similar gene sequences

Question 11

By how much do alleles differ from one another?

Answer 11

By one or a few bases

Question 12

What is an example of a characteristic that the gene has alleles that encode for different colours?

Answer 12

Hair or eye colour

Question 13

What is a gene mutation?

Answer 13

A change in the nucleotide sequence of a section of DNA coding for a specific trait

Question 14

How are new alleles formed?

Answer 14

By mutation

Question 15

What are the three types of gene mutations?

Answer 15

Beneficial
Detrimental
Neutral

Question 16

What do beneficial mutations do?

Answer 16

Change the gene sequence to create new variations of a trait

Question 17

What do detrimental mutations do?

Answer 17

Shorten the gene sequence to stop the normal function of a trait

Question 18

What do neutral mutations do?

Answer 18

Have no effect on the functioning of a specific function

Question 19

What are beneficial mutations also known as?

Answer 19

Missense mutations

Question 20

What are detrimental mutations also known as?

Answer 20

Nonsense mutations

Question 21

What are neutral mutations also known as?

Answer 21

Silent mutations

Question 22

What is an example of a disorder caused by a gene mutation?

Answer 22

Sickle cell anaemia

Question 23

How did the sickle cell anaemia allele arise?

Answer 23

From a base substitution mutation

Question 24

What is a base substitution mutation?

Answer 24

Where a single base is changed in the gene sequence

Question 25

Where is the change that causes sickle cell anaemia?

Answer 25

The 6th codon for the beta chain of haemoglobin

Question 26

How does the DNA sequence change in sickle cell anaemia and on what strand?

Answer 26

The DNA sequence changes from GAG to GTG on the non transcribed strand

Question 27

How does the mRNA sequence change in sickle cell anaemia and in what position?

Answer 27

From GAG to GUG at the 6th codon position

Question 28

What does the polypeptide change from in sickle cell anaemia?

Answer 28

From glutamic acid to valine

Question 29

What does the change from Glu to Val do in sickle cell anaemia?

Answer 29

Alters the structure of haemoglobin causing it to form insoluble fibrous strands

Question 30

What causes an individual suffering from sickle cell to feel constantly tired?

Answer 30

The insoluble haemoglobin cannot carry oxygen as effectively

Question 31

What causes the shape of a red blood cell to a sickle shape in sickle cell anaemia?

Answer 31

The formation of fibrous haemoglobin strands

Question 32

What causes the low red blood cell count in sickle cell anaemia?

Answer 32

Sickle cells are destroyed more rapidly than normal cells

Question 33

What can cause myriad health issues in sickle cell anaemia?

Answer 33

Sickle cells may form clots within the capillaries which blocks blood supply to vital organs

Question 34

What is a genome?

Answer 34

The totality of genetic information of a cell, organism or organelle

Question 35

What does the genome include?

Answer 35

All genes as well as non-coding DNA sequences

Question 36

What does the human genome consist of?

Answer 36

46 chromosomes
3 billion base pairs
21,000 genes

Question 37

What was the human genome project?

Answer 37

An international venture to sequence the human genome

Question 38

What did the human genome project show?

Answer 38

That humans share the majority of their sequence

Question 39

What did the human genome project showed contributed to diversity?

Answer 39

Short nucleotide polymorphisms

Question 40

What were the four outcomes the completion of the human genome project lead to?

Answer 40

Mapping
Screening
Medicine
Ancestry

Question 41

How did the human genome project help with mapping?

Answer 41

The number, location, size and sequence of human genes is now known

Question 42

How did the human genome project help with screening?

Answer 42

It has helped the production of specific gene probes to detect sufferers and carriers of genetic diseases

Question 43

How did the human genome project help with medicine?

Answer 43

The discovery of new proteins has led to improved treatments

Question 44

How has the human genome project helped with ancestry?

Answer 44

Comparisons with other genomes has shown insight into the origins, evolution and migration patterns of man

Question 45

Why is the number of genes present in an organism not a valid indicator of biological complexity?

Answer 45

As the number of genes will differ between species

Question 46

What is the number of genes in a genome usually predicted by?

Answer 46

Identifying sequences common to genes

Question 47

What may identifying regions may include?

Answer 47

Expressed sequence tags or sequences that are homologous to known genes

Question 48

What makes accurate counts of unique gene numbers very difficult?

Answer 48

The presence of pseudogenes and transposons

Question 49

WHy may final estimations of gene numbers vary significantly?

Answer 49

As scientists may use different approaches to predict gene numbers