Topic 3.1 Genes

Question 1

How do you create a new cell from stem cells?

Answer 1

cell differentiation

Question 2

What is a gene?

Answer 2

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

Question 3

What is a locus? (loci for plural)

Answer 3

a specific location on a chromosome for each gene/allele

Question 4

How many chromosomes do we have?

Answer 4

46 (23 pairs)

Question 5

What is an allele?

Answer 5

a variation of the gene for a single trait

Question 6

How do alleles differ from others?

Answer 6

by one or a few bases only

Question 7

How are new alleles formed?

Answer 7

by mutation (affecting the structure or characteristic of a protein)

Question 8

What is deletion? (in base substitution)

Answer 8

when a nucleotide(s) is deleted in a sequence

Question 9

What is sickle cell anemia?

Answer 9

an inherited disease where a mutation in the hemoglobin gene causes it to change shape

Question 10

What are the causes of sickle cell anemia?

Answer 10

• base substitution mutation
• a change to the base sequence of mRNA transcribed from it
• a change to the sequence of a polypeptide in hemoglobin

Question 11

How is the hemoglobin changed?

Answer 11

by a base substitution mutation

Question 12

What is a genome?

Answer 12

the entirety of an organism’s genetic information (DNA in chromosomes) (23 pairs)

Question 13

What was the goal of the Human Genome Project?

Answer 13

to find base sequences in human genes

Question 14

What were the findings of the Human Genome Project?

Answer 14

• 23,000 human genes
• majority of genome is not expressed
• sections have regulatory functions

Question 15

How do the # of genes differ from humans with other species?

Answer 15

Grapes (30,434 genes)
Humans (22,333 genes)
Chicken (16,736)
Fruit Fly (14,889) 
E. coli (4,149) 
Influenza (11)

Question 16

What can online databases help determine?

Answer 16

differences in the base sequence of a gene in 2 species