Brainscape's Knowledge GenomeTM

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


See full index

MED 109- BIOLOGY II > 19. TELOMERES > Flashcards

19. TELOMERES Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q
  1. What are Telomeres?
A
  • they are the ends of Eukaryotic Chromosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  1. What do Telomeres consist of?
A
  • they consist of the following repetitive sequence:
    • (TTAGGG)n
    • this is bound to several proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. What is the role of Telomeres?
A

THEY PROTECT THE CHROMOSOMAL ENDS FROM:
- erosion
- degradation
- recombination with other chromosomes

THEY POSTPONE THE SHORTENING OF DNA MOLECULES:
- they do this by postponing the erosion of the genes
near the ends of the DNA molecules
- they cannot prevent the shortening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. What is the shortening of Telomeres causes by?
A
  • it is caused by cellular ageing
  • this is followed by chromosomal ageing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. What is End-Replication problem?
    (the telomere replication problem)
A
  • there is no Okazaki fragment for the replication of the
    3’ end of the chromosomes
  • this will result in generations of 3’ projections at the
    two 3’ ends
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. What happens with the telomere during DNA Replication?
A

IN EVERY DNA REPLICATION ROUND (S-PHASE):
- a small region of the telomere cannot be replicated

IN EACH CELL DIVISION:
- some base pairs are lost
- about 50-200 base pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  1. Does this diagram make sense?
A
  • yes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. What is Telomerase?
A
  • this is a Ribonucleic enzyme
  • it conserves the Telomere length
  • it prevents the shortening of the telomeres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  1. What is dependent on the length of the Telomeres?
A
  • the Replication Capacity of the cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. What is the role of Telomere shortening?
A
  • it protects cells from Carcinogenesis
  • it does this by limiting the number of cell divisions
  • this is due to Hayflick’s Limit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. What is Hayflick’s Limit?
A
  • is the number of times a normal somatic,
    differentiated human cell population will divide before
    cell division stops

NB:
- this limit does not apply to Stem Cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. What causes the shortening of the Telomerase?
A
  • this shortening is less than 4-7kb
  • it is caused by incomplete replication
  • this results in the chromosome end leading to
    Replicative Senescence
    (this is also known as cellular ageing)
    (this leads to the ageing of the organism)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. What is Senescence?
A
  • this is permanent cell cycle arrest
  • this happens after a cell has reached a certain number
    of cell divisions
  • this is known as Hayflick’s limit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  1. What size should a Telomere be?
A
  • it should be 15-20 kb
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. How does Telomerase prevent the shortening of the Telomere?
A
  • it synthesises the repetitive sequence: TTAGGG
  • this is the sequence of the telomere
  • telomerase synthesises the repetitive sequence by
    using a template RNA Primer
  • it uses this primer PLUS an enzyme called
    Reverse Transcriptase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  1. Can RNA ever be converted to DNA?
A
  • no
17
Q
  1. What are the 2 components that Telomerase consists of?
A
  1. hTERT
    • this is a reverse transcriptase
  2. TEMPLATE RNA PRIMER
    • there is a absence of active telomerase (hTERT) in
      human somatic cells
18
Q
  1. Where do we find Activated Telomerase?
A

IT IS FOUND ONLY IN:
- germ cells
- stem cells
- hair follicle cells (epithelial cell type)
- activated lymphocytes
- several type of cancer cells

19
Q
  1. What does Telomerase protect with regards to gametes?
A
  • it protects the chromosomes of the gametes
20
Q
  1. In which three cells is there regulation of Telomerase Activity?
A
  1. Normally Active in Germ Cells
  2. Normally Inactive in most types of Somatic Cells
  3. Abnormally active in some cancer cells
21
Q
  1. Why is it normal that Telomerase is active in Germ cells?
A

IF THE CHROMOSOMES OF GERM CELLS BECAME SHORTER IN EVERY CYCLE:
- the essential genes would eventually be missing from
the gametes that they produce

NB:
- sperm and egg cells need a good chromosomal
structure

22
Q
  1. Why is it normal for Telomerase to be inactive in most types of Somatic Cells?
A

EXCEPT FOR:
- stem cells
- hair follicle cells
- activated lymphocytes

23
Q
  1. Why is it Abnormal for Telomerase to be active in some cancer cells?
A
  • this may allow for the cancer to persist
  • this will cause continuous proliferation
24
Q
  1. Does this diagram make sense?
A
  • yes

MED 109- BIOLOGY II (90 decks)

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