Lecture 16

Question 1

Heredity?

Answer 1

The passing on of physical or mental characteristics genetically from one generation to another

Question 2

Where is our genetic information stored?

Answer 2

In the nucleus as DNA

Question 3

Genotype?

Answer 3

• Genetic constitution of the cell

- A set of traits

Question 4

Phenotype?

Answer 4

Phenotype = genotype + environment

• The physical expression of the genotype (what you see )

Question 5

How many chromosomes do humans have?

Answer 5

22 identical pairs of chromosomes (autosomes)

1 pair of sex chromosomes (allosomes)

Question 6

What does increasing the packing of DNA decrease?

Answer 6

Decreases gene expression due to reduced accessibility

Question 7

When is DNA most active?

Answer 7

• In an uncondensed form

- Gene expression

Question 8

When is DNA most unactive?

Answer 8

• In an condensed form
• No gene expression
• e.g chromosome

Question 9

What does a DNA helix wrap around to condense itself?

Answer 9

Histone proteins

Question 10

Information flow?

Answer 10

DNA-Transcription-mRNA-Translation-Polypeptide

Question 11

Genome?

Answer 11

Library of genes

Question 12

Purines?

Answer 12

• Adenine and guanine

- Double ring

Question 13

Pyrimidines?

Answer 13

• Thymine and cytosine

- Single ring

Question 14

What is DNA?

Answer 14

A polymer that consists of nucleotides (bases = a,t,g,c)

Question 15

What is each DNA strand made up of?

Answer 15

• Base
• Sugar
• Phosphate

Question 16

Composition of the DNA helix?

Answer 16

• Two polynucleotide strands are wound together about a common axis (anti parallel orientation)
• A sugar-phosphate backbone on the exterior of the helix
• Purine and pyrimidine nucleotide bases are on the interior of the helix

Question 17

What are the two grooves that that twisting strands of DNA have?

Answer 17

• Major groove

- Minor groove (sugar-phosphate backbone runs closer together here)

Question 18

How many hydrogen bonds hold a and t together?

Answer 18

2

Question 19

How many hydrogen bonds hold g and c together?

Answer 19

• 3

- Requires more energy to break cytosine and guanine apart

Question 20

What is the direction of a DNA strand?

Answer 20

5 prime to 3 prime

Question 21

What does 5 prime and 3 prime mean?

Answer 21

Describes the two main positions of carbon that are involved in the synthesis of DNA

Question 22

What is the direction of that DNA is transcribed from?

Answer 22

5 prime to 3 prime

Question 23

When does DNA replication happen?

Answer 23

During s-phase of interphase

Question 24

What type of process is DNA replication?

Answer 24

A semiconservative process where a parental strand (template) is used to create a new complementary daughter strand