Chapter 11: Chromosome Structure and Organelle DNA Flashcards
The endosymbiotic theory included what two organelles? What is unique about these two organelles?
mitochondria and chloroplasts
Each have circular DNA and their own set of DNA
True or False: The centromere can be found in different locations of the chromosome?
True
What are the 4 locations a centromere can be found on a chromosome? Provide a rough description of their location.
- 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)
What letters can be used to represent the short arm and long arm of the chromosome?
p = short arm
q = long arm
What component of the chromosome is the primary cause of aging?
telomere decay or degradation
What is a disc-shaped protein structure located on the centromere which helps spindle fibers attach and pull chromosomes apart?
Kinetochore
Which kind of supercoiling occurs when DNA is under-rotated and the helix twists on itself in the opposite direction?
negative supercoiling
What kind of supercoiling occurs when DNA is over-rotated and the helix twists on itself?
positive supercoiling
Most DNA is _______ supercoiled, which facilitates DNA unwinding during replication and transcription.
negatively (-ve)
Relaxed circular DNA can be compared to a telephone cord; explain why this is.
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.
Since bacteria do not have a well-defined nucleus, they instead have a clump of chromosomes called a ______.
nucleolid
Bacterial DNA does have proteins packed into twisted loops, but what kind of specific proteins do bacterial DNA NOT have?
histone proteins
True or False: Bacterial cells have more DNA in them than eukaryotic cells.
False; Eukaryotic cells have LOADS more DNA than bacterial cells due to extensive packaging and folding.
What are the specific packaging proteins for eukaryotic DNA?
histones
What is the largest cell in the world?
an ostrich egg
What kind of chromatin is located in the chromosome arms?
euchromatin
What kind of chromatin is located in the centromere, telomeres and other specific places?
heterochromatin
Euchromatin or Heterochromatin: Which has many genes and which has few genes?
- euchromatin: many genes
- heterochromatin: few genes
Euchromatin or Heterochromatin: Which one does transcription take place the most?
euchromatin
Euchromatin or Heterochromatin: Which one does not code for genes?
heterochromatin
What is the simplest form of chromatin?
double-stranded helical structure of DNA
In the formation of chromosomes, DNA and histones are complexed to form ________.
nucleosomes
Each nucleosome consists of how many histone proteins? How many times does DNA wrap around this complex?
8 histones
1.65 times
Which histone acts as a “clip” for the wrapped DNA in a nucleosome?
Histone H1
Nucleosomes fold up to produce a 30-nm ____.
fiber
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 ____.
loops, fiber
During the formation of chromosomes, what happens once a 250-nm wide fiber is created?
The fiber is further condensed into chromosomes.
What enzyme breaks the Linker DNA between nucleosomes?
nuclease
What is the charge of histone proteins, and why?
positively charged, high percentage of positive valence electrons of amino acids.
What would happen if the charge of histones was neutralized?
They wouldn’t be able to bond as tightly to the DNA
What are the five types of histones? Which are duplicated?
H1, H2A, H2B, H3, H4
duplicated: H2A, H2B, H3, H4
Centromeres help control the cell cycle by doing what?
Causing DNA without centromeres to be lost
What is the separation of two strands of DNA by heat?
denaturation
Which strand of DNA would have a higher melting point? G-C bonds or A-T bonds?
G-C bonds
What evidence supports the endosymbiotic theory?
- 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
How is mtDNA (mitochondrial DNA) inherited in offspring?
The mother’s mitochondrial DNA is what is inherited
