molbio

Question 1

What is the total number of nucleotide base pairs in human DNA?

Answer 1

2.9 billion nucleotide base pairs of DNAs organized in 23 chromosomes

Question 2

How many chromosomes do diploid organisms have?

Answer 2

46 chromosomes

Question 3

What is the structure of each chromosome?

Answer 3

Each chromosome is a double helix of DNA

Question 4

Which chromosome is the largest in humans?

Answer 4

Chromosome 1

Question 5

Which chromosome is the smallest in humans?

Answer 5

Chromosome 21

Question 6

Define POLYMORPHISM in genetics.

Answer 6

A difference in DNA sequence found in 1%-2% or more of a given population

Question 7

What are examples of polymorphisms?

Answer 7

• Blood types in humans
• Color of hair & eyes
• Separation of higher organisms into male & female sexes
• Polymorphisms used for human ID & paternity testing

Question 8

Define MUTATION in genetics.

Answer 8

A change in the order/sequence of nucleotide in DNA found in <1%-2% of a given population

Question 9

What can cause mutations?

Answer 9

• Errors in DNA replication
• Exposure to mutagens
• Other factors

Question 10

What is BALANCED POLYMORPHISM?

Answer 10

Maintained in a population through a balance of positive & negative phenotype

Question 11

How does SICKLE CELL ANEMIA provide an example of balanced polymorphism?

Answer 11

Abnormal RBCs resulting in resistance to infection by Plasmodium species (malaria)

Question 12

Define BENIGN POLYMORPHISM.

Answer 12

Does not have any detectable negative effects on an organism’s health/fitness

Question 13

What are characteristics of benign polymorphisms?

Answer 13

• Typically common in populations
• Do not lead to disease/other adverse phenotypic outcomes

Question 14

Give examples of benign polymorphisms.

Answer 14

• Blood type (ABO blood group)
• Eye color
• Facial features
• Skin pigmentation

Question 15

What are the classifications of mutations?

Answer 15

• Gene mutations
• Chromosome mutations
• Genome mutations

Question 16

What do gene mutations affect?

Answer 16

Affect single genes & are often, but not always, small changes in the DNA sequence

Question 17

What do chromosome mutations affect?

Answer 17

Affect the structures of entire chromosomes

Question 18

What are genome mutations?

Answer 18

Changes in the number of chromosomes (aneuploidy)

Question 19

Define CHROMOSOMAL COMPACTION.

Answer 19

Process by which the long, linear DNA molecules of eukaryotic chromosomes are organized & packaged into highly condensed structures

Question 20

What affects chromosome behavior?

Answer 20

Chromosome structure & DNA sequences (position effect)

Question 21

How does chromosome topology affect gene activity?

Answer 21

Highly compacted DNA = less available for RNA transcription

Question 22

Why are DNA strands condensed into compact chromosomes?

Answer 22

To fit in the cell’s nucleus