Unit 2, part 1

Question 1

What carries genetic information for the development and function of an organism?

Answer 1

Nucleic Acids

Nucleic acids serve as the instruction manual for cells.

Question 2

What are the four major biomolecule groups?

Answer 2

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

These groups are fundamental to biological processes.

Question 3

Define monomer.

Answer 3

A small molecule that acts as a building block

Monomers combine to form polymers.

Question 4

Define polymer.

Answer 4

A long chain molecule made up of repeating patterns of monomers

Examples include nucleic acids, proteins, and carbohydrates.

Question 5

What are the building blocks of nucleic acids?

Answer 5

Nucleotides

Nucleotides are composed of a sugar, a phosphate group, and a nitrogenous base.

Question 6

What distinguishes Deoxyribose Nucleic Acid from Ribose Nucleic Acid?

Answer 6

Deoxyribose has one less oxygen atom than ribose

This difference impacts the stability and structure of the nucleic acids.

Question 7

Name the two types of nitrogenous bases.

Answer 7

• Purines (2 rings)
• Pyrimidines (1 ring)

Purines include adenine and guanine; pyrimidines include cytosine, thymine, and uracil.

Question 8

What is the primary structure of DNA?

Answer 8

Polynucleotide strand

This structure is a linear sequence of nucleotides linked by phosphodiester bonds.

Question 9

What is the secondary structure of DNA?

Answer 9

Double Helix

DNA is always found double-stranded for stability.

Question 10

What are the rules for double-stranded DNA base pairing?

Answer 10

• Equal amounts of A and T
• Equal amounts of G and C
• Equal amounts of purines and pyrimidines

These rules are due to DNA’s complementary nature.

Question 11

What is the tertiary structure of DNA?

Answer 11

3D structure formed by base pair interactions

The B-form of DNA is the most common and stable configuration.

Question 12

Who was key to discovering the double helix structure of DNA?

Answer 12

Rosalind Franklin

Her X-ray diffraction images were critical in elucidating the DNA structure.

Question 13

What is the quaternary structure of nucleic acids?

Answer 13

Interactions of nucleic acids with other molecules

This includes interactions with proteins or other nucleic acids.

Question 14

How is DNA packaged in a cell?

Answer 14

• Nonreplicated chromosome: 1 single DNA molecule of chromatin
• Nucleosomes: DNA wrapped around histones
• Chromatin fiber: compacted structure of nucleosomes

Supercoiling during cell division forms the most condensed form of chromatin.

Question 15

What are the characteristics of euchromatin?

Answer 15

• Less condensed
• Changes with the cell cycle
• Often transcribed

Euchromatin is found on chromosome arms and contains many genes.

Question 16

What are the characteristics of heterochromatin?

Answer 16

• Highly condensed
• Infrequent transcription
• Found at centromeres and telomeres

Heterochromatin contains few genes and is always in a condensed state.

Question 17

What is histone acetylation?

Answer 17

Modification that reduces the positive charge on histones

This loosens histones’ grip on DNA, facilitating transcription.

Question 18

What is DNA methylation?

Answer 18

Addition of methyl groups to DNA that blocks transcription

This process affects gene expression and can be passed to the next generation.

Question 19

True or False: Chromatin can change throughout the cell cycle.

Answer 19

True

Chromatin relaxes for transcription and translation.

Question 20

Fill in the blank: A base and a sugar is known as a _______.

Answer 20

Nucleoside

Nucleosides do not include the phosphate group.

Question 21

How many DNA molecules are in a replicated chromosome?

Answer 21

2

Each replicated chromosome consists of two identical sister chromatids.