Chapter 11: Chromosome Structure and Organelle DNA

Question 1

The endosymbiotic theory included what two organelles? What is unique about these two organelles?

Answer 1

mitochondria and chloroplasts
Each have circular DNA and their own set of DNA

Question 2

True or False: The centromere can be found in different locations of the chromosome?

Answer 2

True

Question 3

What are the 4 locations a centromere can be found on a chromosome? Provide a rough description of their location.

Answer 3

• Metacentric: dead center of the chromosome
• Sub-metacentric: a bit above the center of the chromosome
• Acrocentric: above the sub-metacentric location
• Telocentric: at the tip of the chromosome (telomeres)

Question 4

What letters can be used to represent the short arm and long arm of the chromosome?

Answer 4

p = short arm
q = long arm

Question 5

What component of the chromosome is the primary cause of aging?

Answer 5

telomere decay or degradation

Question 6

What is a disc-shaped protein structure located on the centromere which helps spindle fibers attach and pull chromosomes apart?

Answer 6

Kinetochore

Question 7

Which kind of supercoiling occurs when DNA is under-rotated and the helix twists on itself in the opposite direction?

Answer 7

negative supercoiling

Question 8

What kind of supercoiling occurs when DNA is over-rotated and the helix twists on itself?

Answer 8

positive supercoiling

Question 9

Most DNA is _______ supercoiled, which facilitates DNA unwinding during replication and transcription.

Answer 9

negatively (-ve)

Question 10

Relaxed circular DNA can be compared to a telephone cord; explain why this is.

Answer 10

DNA is in the form of a double helix, so as the DNA is wound in a circle, the double helix is coiled itself in a spiral.

Question 11

Since bacteria do not have a well-defined nucleus, they instead have a clump of chromosomes called a ______.

Answer 11

nucleolid

Question 12

Bacterial DNA does have proteins packed into twisted loops, but what kind of specific proteins do bacterial DNA NOT have?

Answer 12

histone proteins

Question 13

True or False: Bacterial cells have more DNA in them than eukaryotic cells.

Answer 13

False; Eukaryotic cells have LOADS more DNA than bacterial cells due to extensive packaging and folding.

Question 14

What are the specific packaging proteins for eukaryotic DNA?

Answer 14

histones

Question 15

What is the largest cell in the world?

Answer 15

an ostrich egg

Question 16

What kind of chromatin is located in the chromosome arms?

Answer 16

euchromatin

Question 17

What kind of chromatin is located in the centromere, telomeres and other specific places?

Answer 17

heterochromatin

Question 18

Euchromatin or Heterochromatin: Which has many genes and which has few genes?

Answer 18

• euchromatin: many genes
• heterochromatin: few genes

Question 19

Euchromatin or Heterochromatin: Which one does transcription take place the most?

Answer 19

euchromatin

Question 20

Euchromatin or Heterochromatin: Which one does not code for genes?

Answer 20

heterochromatin

Question 21

What is the simplest form of chromatin?

Answer 21

double-stranded helical structure of DNA

Question 22

In the formation of chromosomes, DNA and histones are complexed to form ________.

Answer 22

nucleosomes

Question 23

Each nucleosome consists of how many histone proteins? How many times does DNA wrap around this complex?

Answer 23

8 histones
1.65 times

Question 24

Which histone acts as a “clip” for the wrapped DNA in a nucleosome?

Answer 24

Histone H1

Question 25

Nucleosomes fold up to produce a 30-nm ____.

Answer 25

fiber

Question 26

During the formation of chromosomes, once the 30-nm fiber is created, 300-nm ___ are created, and then they condense even farther to produce a 250-nm wide ____.

Answer 26

loops, fiber

Question 27

During the formation of chromosomes, what happens once a 250-nm wide fiber is created?

Answer 27

The fiber is further condensed into chromosomes.

Question 28

What enzyme breaks the Linker DNA between nucleosomes?

Answer 28

nuclease

Question 29

What is the charge of histone proteins, and why?

Answer 29

positively charged, high percentage of positive valence electrons of amino acids.

Question 30

What would happen if the charge of histones was neutralized?

Answer 30

They wouldn’t be able to bond as tightly to the DNA

Question 31

What are the five types of histones? Which are duplicated?

Answer 31

H1, H2A, H2B, H3, H4
duplicated: H2A, H2B, H3, H4

Question 32

Centromeres help control the cell cycle by doing what?

Answer 32

Causing DNA without centromeres to be lost

Question 33

What is the separation of two strands of DNA by heat?

Answer 33

denaturation

Question 34

Which strand of DNA would have a higher melting point? G-C bonds or A-T bonds?

Answer 34

G-C bonds

Question 35

What evidence supports the endosymbiotic theory?

Answer 35

• mitochondria & chloroplasts are similar in size to bacteria with their own DNA
• antibiotics that inhibit protein synthesis in bacteria also inhibit protein synthesis in mitochondria & chloroplasts
• gene sequences in mtDNA and cpDNA are most similar to bacterial DNA sequences

Question 36

How is mtDNA (mitochondrial DNA) inherited in offspring?

Answer 36

The mother’s mitochondrial DNA is what is inherited