2.1: Genes

Question 1

Locus

Answer 1

specific location/ position of a gene on a chromosome

Question 2

allele

Answer 2

variation of a gene differing by one or two bases

Question 3

Mutation

Answer 3

1. errors in the genetic code created during replication, resulting in a daughter cell with DNA differing from the parent cell
2. driving force of evolution
3. reason for species differences
4. may change function of encoded protein or can be silent

Question 4

Mutagens

Answer 4

1. agent that changes genetic material

2. can be physical, chemical or biological

Question 5

point mutation

Answer 5

a mutation that modifies a single nucelotide in a sequence through substitution, insertion or deletion

Question 6

Missense mutation

Answer 6

a single amino acid is changed

Question 7

nonsense mutation

Answer 7

a stop codon is created, shortening the polypeptide

Question 8

Intron

Answer 8

non-coding DNA

Question 9

Exon

Answer 9

coding/ expressed DNA

Question 10

Genes

Answer 10

heritable factor that consists of a length of DNA and influences a specific characteristic

Question 11

Diploid

Answer 11

a pair of each kind of chromosome

Question 12

homozygous

Answer 12

two copies of the same allele

Question 13

heterozygous

Answer 13

two different alleles

Question 14

genotype

Answer 14

alleles you have for a gene

Question 15

phenotype

Answer 15

Physical trait expressed as a result of your alleles

Question 16

Base substitution mutation

Answer 16

mutation that changes one nitrogenous base in a sequence

Question 17

the human genome project

Answer 17

1. Began in 1990 to determine the complete sequence of the human genome and identify every gene it contained
2. 3.2 billion bases
3. finished in 2003, 2 years ahead of schedule

Question 18

protein cofing genes in E-coli

Answer 18

4000 n=1

Question 19

protein coding genes in humans

Answer 19

20 000 n=46

Question 20

protein coding genes in rice

Answer 20

35 000 n=24

Question 21

larger genomes contain [____]

Answer 21

high portion of non-coding genes

Question 22

Sickle cell anemia symptoms

Answer 22

crisis events of extreme pain, weakness, stroke, heart attack, pneumonia, bone malformations, death

Question 23

sickle cell anemia cause

Answer 23

1. base substitution mutation
2. chromosome 11, HBB gene (codes for beta subunit of hemoglobin)
3. 6th triplet of the DNA sense strand
4. substitute adenine for thymine creating Hb^s gene rather than Hb^a

Question 24

Sickle cell anemia codons and amino acids

Answer 24

1. healthy = GAG = glutamic acid

2. sickle cell = GTG (GUG) = valine

Question 25

Hemoglobin made of

Answer 25

2 beta subunit, 2 alpha subunit, combines 2ith 4 heme group

Question 26

sickle cell hemoglobin

Answer 26

hydrophobic valine makes hemoglobin polymerise into long fibres that are less efficient at carrying oxygen and poke the cell membrane, distorting the shape to the sickle appearance

Question 27

impact of sickle shape

Answer 27

1. clog blood vessel, causing pain and stroke
2. expelling sickle cells strains the liver
3. expelled cells leads to shortage of erythrocytes = anemia

Question 28

Pleiotropy

Answer 28

multiple effects from a single gene

Question 29

Sickle anemia (full) occurs when

Answer 29

person is homozygous for Hb^s

Question 30

Hb^a Hb^a

Answer 30

no sickle cell

Question 31

heterozygous Hb^s Hb^a

Answer 31

some beta cells with valine, some with glutanic acid

Question 32

Sickle cell and malaria

Answer 32

1. cells sickle when infected with the parasite that causes malaria
2. body eliminates sickle cells, thereby eliminating malaria
3. where malaria is present, heterozygous Hb^s allele is a genetic advantage