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Question 1

What are the three main components of a nucleotide?

Answer 1

1. A pentose sugar
2. A phosphate group
3. Nitrogenous base

Question 2

What is complementary base pairing in DNA?

Answer 2

In DNA, adenine (A) pairs with thymine (T) via two hydrogen bonds - and guanine (G) pairs with cytosine (C) via three hydrogen bonds

Question 3

What type of bond holds the two strands of DNA together?

Answer 3

Hydrogen bonds between complementary nitrogenous bases

Question 4

What is the significance of DNA being antiparallel?

Answer 4

The two DNA strands run in opposite directions, meaning one strand runs 5’ to 3’ and the complementary strand runs 3’ to 5’

Question 5

What is the sugar-phosphate backbone in DNA?

Answer 5

The sugar-phosphate backbone is the repeating structure of sugar (deoxyribose) and phosphate that forms the outer structure of DNA, with the nitrogenous bases pointing inward

Question 6

What is a chromosome?

Answer 6

a long strand of DNA tightly packed with proteins, mainly histones, that carry genetic information

Question 7

What is chromatin?

Answer 7

Chromatin is the material that makes up chromosomes, consisting of DNA and histone proteins

Question 8

What is the role of histones in DNA packaging?

Answer 8

Histones are proteins around which DNA wraps to form nucleosomes, the basic units of chromatin structure, aiding in DNA condensation and accessibility

Question 9

What is a nucleosome?

Answer 9

A nucleosome is a structural unit of chromatin, consisting of DNA wrapped around a core of eight histone proteins

Question 10

How do histones and DNA interact?

Answer 10

DNA, which is negatively charged due to its phosphate groups, wraps around positively charged histones, which contain basic amino acids like lysine and arginine

Question 11

What is the first level of DNA packaging in eukaryotic chromosomes?

Answer 11

DNA wraps around histone proteins to form nucleosomes, which are the first level of packaging

Question 12

What is the 30 nm fiber in chromosome structure?

Answer 12

The 30 nm fiber is a further condensed form of chromatin, where nucleosomes are packed together with the help of histone H1

Question 13

How is chromatin made dynamic to allow replication and transcription?

Answer 13

Chromatin is made dynamic through chromatin remodeling complexes and histone modifications, such as acetylation, which loosen or tighten the chromatin structure

Question 14

What is the role of histone acetylation?

Answer 14

Acetylation of histone tails neutralizes the positive charge, loosening the interaction between histones and DNA, thus making the chromatin more accessible for transcription

Question 15

What are the key structural components of a eukaryotic chromosome that ensure its replication and separation?

Answer 15

The telomere (protects the ends of chromosomes and allows for complete replication), the replication origin (where replication begins), and the centromere (attaches to mitotic spindles during cell division)

Question 16

What is the function of the nuclear membrane?

Answer 16

The nuclear membrane (or nuclear envelope) consists of two concentric membranes that separate the nucleus from the cytoplasm and contains nuclear pores for selective transport

Question 17

What is the function of the nucleolus?

Answer 17

The nucleolus is the site of ribosomal RNA (rRNA) synthesis and the assembly of ribosomal subunits

Question 18

What is the difference between interphase and M-phase chromosomes?

Answer 18

Interphase chromosomes are less condensed and allow for gene expression and replication, while M-phase chromosomes are highly condensed to facilitate segregation during cell division

Question 19

What is the genome?

Answer 19

The genome is the complete set of genetic information in an organism’s DNA

Question 20

What causes the uniform diameter of the DNA double helix?

Answer 20

The pairing of purines (adenine and guanine) with pyrimidines (thymine and cytosine) ensures a uniform diameter, with A pairing with T and G pairing with C

Question 21

What role do nuclear pores play in the cell?

Answer 21

Nuclear pores act as selective channels that regulate the movement of molecules, such as RNA and proteins, between the nucleus and the cytoplasm

Question 22

How long is the total length of DNA in a single human cell?

Answer 22

Approximately 2 meters of DNA are packed into each human cell

Question 23

What is the challenge related to packaging DNA into chromosomes?

Answer 23

The challenge is to compact the 2 meters of DNA into a nucleus that is only about 5 µm in diameter, while still maintaining accessibility for replication and transcription

Question 24

How do chromatin remodeling complexes affect DNA packaging?

Answer 24

Chromatin remodeling complexes reposition or restructure nucleosomes to allow greater accessibility to DNA, facilitating processes like replication and transcription

Question 25

What is the significance of telomeres on chromosomes?

Answer 25

Telomeres protect the ends of chromosomes from degradation and ensure that the entire length of the chromosome is replicated

Question 26

What is the role of centromeres during cell division?

Answer 26

Centromeres are DNA sequences that allow chromosomes to attach to mitotic spindles during cell division, ensuring proper chromosome segregation

Question 27

What is chromatin made of?

Answer 27

Chromatin consists of DNA and proteins, primarily histones, which help in the compaction and organization of DNA within the nucleus

Question 28

What happens during histone deacetylation?

Answer 28

Histone deacetylation removes acetyl groups from histones, restoring their positive charge, which leads to tighter chromatin packing and inhibits transcription

Question 29

Why do purines always pair with pyrimidines in DNA?

Answer 29

Purines (adenine and guanine) are larger, two-ring structures, while pyrimidines (thymine and cytosine) are smaller, single-ring structures. Pairing them maintains the uniform diameter of the DNA double helix

Question 30

Why is DNA packaging dynamic, and why is this important for the cell?

Answer 30

DNA packaging must be dynamic to allow for gene expression, replication, and repair, which require access to specific regions of the DNA at different times

Question 31

What is the function of histone H1?

Answer 31

Histone H1 helps pull nucleosomes together, forming a more condensed 30 nm fiber, which is an important step in chromatin packaging

Question 32

How many histone proteins make up the core of a nucleosome?

Answer 32

The nucleosome core consists of 8 histone proteins (2 copies each of H2A, H2B, H3, and H4)

Question 33

What happens to chromosomes during the M-phase of the cell cycle?

Answer 33

Chromosomes become highly condensed to ensure accurate segregation during mitosis