Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CELLULAR AND MOLECULAR BIOLOGY > CHROMOSOME STRUCTURE > Flashcards

CHROMOSOME STRUCTURE Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Individual chromosomes can be easily distinguished at what phase of mitosis?

A

Metaphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What method can be used to visualise chromosomes?

A

Chromosome painting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Each chromosome pair differs in what?

A

DNA sequence content

Size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a karyotype?

A

An organised representation of all of the chromosomes in a eukaryotic cell at metaphase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can karyotyping be used for?

A

Can be used to find abnormalities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does an interphase nucleus look like?

A

An interphase nucleus is a large mass of chromosomes in an organised manner. Individual chromosomes occupy distinct subnuclear territories.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a chromosome?

A

A highly coiled fibre of chromatin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What can chromatin alternate between?

A

10nm coiled fibre and 30nm coiled fibre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are 10nm fibre chromatin made up of?

A

DNA wraps around histone proteins -this is euchromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are 30nm fibre chromatin made up of?

A

multiple histones wrap into 30nm conisisting of nucleosome arrays in their most compact form - this is heterochromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Higher level DNA supercoiling of the 30nm fibre produces what?

A

The metaphase chromosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the roles of 10nm and 30nm chromatin?

A

The chromatin can be uncoiled for the molecules of transcription/repairs etc can access the DNA and vice/versa.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a nucleosome?

A

A nucleosome is made up of just under two turns of DNA wrapped around a histone octamer (a set of 4 proteins making up two discs.). The N termainal tails of the 8 core histone subunits project out and are free to interact with other proteins, facilitating regulation of chromatin structure and function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What feature of histone octamers means they can interact well with the phosphodiester backbone of DNA?

A

The histones are highly basic (+ve) and can interact with the
-ve DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do histones and chromatin stay bound?

A

By electrostatic attractions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a linker histone?

A

They strap DNA onto histone octamers to limit movement of DNA relative to the histone octamer.
Acts like a clip.
Stabilising formation of 30nm fibre.
DNA rich in linker histones such as H1 is transcriptionally inactive.

17
Q

Regions of chromatin where histone octamers are depleted means what?

A

That region of DNA will be susceptible to DNA interacting proteins.

18
Q

Interphase chromatin comprises of chromatin that can reversibly condense and decondesnse without become knotted. What is this called?

A

Fractal globules

19
Q

What happens to fractal globules?

A

They can be pushed around the nucleus to areas where RNA/DNA polymerase are in high concentration for transcription. Usually heterochromatin sits on the periphery of the nucleus and moved to the centre of the nucleus when there is transciptional activation of a gene.

20
Q

Chromosomes contain specialised DNA sequences that facilitate reliable and complete DNA replication and segregation of duplicated chromosomes during cell division. What are some examples of said DNA sequences?

A

Telomeres
Replication Origins
Centromeres

21
Q

What is a telomere?

A

repeated DNA sequences at the ends of linear chromosomes that maintain chromosomal integrity
consist of TTAGGG

22
Q

What is a replication origin?

A

DNA sequence where DNA replication is initiated.

23
Q

What is a centromere?

A

DNA sequences on which kinetochore assembles and mediates chromosome segregation at mitosis and meiosis.

24
Q

What is a kinetochore?

A

Protein complex that binds microtubules on the mitotic spindle.

25
Q

What is the role of telomeres?

A

At the end of DNA replication, there is an overhang due to RNA primer. If this were left, the overhand would be digested and information would be lost. Telomerase adds repeats to preserve integrity.

26
Q

What are centromeres made up of?

A

Centromeres are alpha satellite DNA repeats for which the inner plate of the kinetochore can bind to.

27
Q

What does outer plate kinetochore bind to?

A

Kinetochore proteins bind to the microtubules of the mitotic spindle.

28
Q

Microtubules dock onto the outer plate of the kinetochore which is glued to the inner kinetochore plate. How does the inner plate of the kinetochore bind with the centromeric regions?

A

The centromeric regions contains a specific histone variant called centromeric protein - A that makes a specific series of contacts with the inner kinetochore plate.

29
Q

In yeast, how do the kinetochore like with the centromere?

A

The kinetochore is in a basket arrangements that holds a single microtubule in one end and attaches to a single nucelosome of centromeric chromatin.

30
Q

How much of the human genome encode information for making cellular proteins?

A

1.5%

31
Q

50% of the genome is made up of unique coding sequences. What do these sequence for?

A
  1. Protein Coding Regions
  2. Introns
  3. Non-repetitive DNA that is neither introns nor codons.
32
Q

Out of the 50% of DNA that is made up of unique sequences, approximately 30/50% is made up of non repetitive DNA that is neither codons nor introns. What is it?

A

It is thought to be cis regulatory DNA that acts on genes nearby.
The more protein coding genes there are, the more non coding regulatory DNA there is.

33
Q

The other 50% of the human genome is made up of repeated sequences. What are these made up of?

A
  1. Simple Sequence Repeats
  2. Segmental Duplications
  3. Transposons
34
Q

Most of the 50% of repeated DNA in the human genome is made up of Transposons. What kinds of Transposons are there?

A
  1. DNA Transposons
  2. Retroviral Transposons
  3. Non Retroviral PolyA Retrotransposons
35
Q

What are transposons?

A

Mobile genetic elements that jump around the genome.

36
Q

How do DNA Transposons work?

A

They move by a cut and paste mechanism without self duplication by transposase.
Once cut from the strand it undergoes self repair.
The cut transposome randomly inserts elsewhere into the genome.

37
Q

How do retroviral retrotransposons work?

A

Replicate via RNA intermediates producing new DNA copies that integrate at new genomic locations using self encoded reverse transcriptase.

38
Q

How do non retroviral polyA retrotransposons work?

A

Replicates via an RNA intermediate using self encoded reverse transcriptase
Binds to DNA producing a second strand which is then inserted.
These code from SINEs and LINEs.

39
Q

What is the purpose of transposons?

A

It is not understood, but theoretically, this helps to drive evolution.

CELLULAR AND MOLECULAR BIOLOGY (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions