3.1 & 3.2 chromosomes and genes

Question 1

gene

Answer 1

a sequence of DNA that encodes for a certain trait. They are heritable

Question 2

locus

Answer 2

describes the position of a gene on a certain chromosome

Question 3

allele

Answer 3

diff forms of a gene

Question 4

how are new alleles formed?

Answer 4

mutations

Question 5

allele for sickle cell anemia

Answer 5

HBB found on chromosome 11

Question 6

how is the sickle cell allele created?

Answer 6

A mutation of one base pair on the 6th codon

Question 7

which amino acid is substituted in the sickle cell allele?

Answer 7

The 6th amino acid, glutamic acid, is substituted with valine

Question 8

how many homologous chromosomes need to carry the sickle cell allele for a person to have sickle cell anemia?

Answer 8

both chromosomes

Question 9

heterozygous advantage

Answer 9

People who carry one normal allele and one sickle cell allele on each homologue will mostly produce normal blood cells and some sickle blood cells. They are healthy. These sickle cells provide an increased resistance against the malaria parasite

Question 10

gene mutation

Answer 10

a change in the base sequence of DNA

Question 11

3 types of gene mutations

Answer 11

Beneficial - add new variations of a trait
Detrimental - can disrupt the normal function of that gene
Neutral - have no impact on the normal function of that gene

Question 12

genome

Answer 12

the totality of genetic information in an organism (or cell)

Question 13

human genome consists of:

Answer 13

46 chromosomes
~6 billion base pairs
~21,000 genes

Question 14

draw E. coli (prokaryotic cells

Answer 14

see ipad

Question 15

how is DNA in prokaryotes structured?

Answer 15

• linear/rod-shaped
• 1 chromosome
• Circular plasmids
• Double-stranded and naked (not associated w/ histone proteins)

Question 16

how many chromosomes do prokaryotes have?

Answer 16

1 (circular), found in nucleoid

Question 17

how many bases does a prokaryotic chromosome have?

Answer 17

6,600 to 12,200,000; 1 copy of each gene

Question 18

plasmid

Answer 18

an independent, small circle of DNA

Question 19

what do plasmids do for prokaryotic cells?

Answer 19

can contain genes for antibiotic resistance; can be transferred (transformation, transduction, conjugation).

Question 20

how is DNA in eukaryotes structured?

Answer 20

Eukaryote chromosomes are linear DNA molecules associated with histone proteins

Question 21

What part of the cell cycle does a cell need to be in in order to produce a karyogram?

Answer 21

metaphase

Question 22

how are karyotypes constructed from a fetus?

Answer 22

Amniocentesis. This procedure collects a sample of the amniotic fluid that surrounds the unborn baby during pregnancy

Question 23

Technique for measuring length of DNA molecules by autoradiography (Cairn’s technique)

Answer 23

• Cells grown in medium with radioactive thiamine (T)
• DNA (w/ ra Thiamine) separated out
• Washed w/ a solution containing silver ion (Ag+)
• Plated on film and x-rayed (autoradiograph)
• Measure length of DNA strands

Question 24

evidence provided by Cairn’s technique

Answer 24

• Chromosome length (uncoiled)
• Bacterial DNA replication forms a replication bubble
• Eukaryotic DNA replication forms a replication fork and is bidirectional