U4: CHROMOSOMES BASED ON CENTROMERE POSITION Flashcards
Centromere is centrally located or in the middle, yielding arms of roughly equal length
Metacentric
Pairs of metacentric chromosomes in human
5
1st chromosome
Metacentric
3rd chromosome
Metacentric
16th chromosome
Metacentric
19th chromosome
Metacentric
20th chromosome
Metacentric`
1st, 3rd, 16th, 19th, 20th chromosome
Metacentric
Shape of spindle fiber in Metacentric
V-shaped
Centromere is off-center, q arm is longer and shorter p arm, has unequal length of chromosome arms
Submetacentric
Shape of spindle fiber in Submetacentric
J-shaped
2nd chromosome
Submetacentric
4th chromosome
Submetacentric
7th chromosome
Submetacentric
12th chromosome
Submetacentric
17th chromosome
Submetacentric
18th chromosome
Submetacentric
2nd, 4th to 12th, 17th, 18th, X chromosome
Submetacentric
Pairs of submetacentric chromosomes in human
13
X chromosome
Submetacentric
The centromere is very close to one end, yielding a small p arm
Acrocentric
This means peak
acro
Often associated with satellites encoding rRNA
Acrocentric
Pairs of acrocentric chromosomes in human
5
13th chromosome
Acrocentric
14th chromosome
Acrocentric
15th chromosome
Acrocentric
21th chromosome
Acrocentric
22nd chromosome
Acrocentric
Y chromosome
Acrocentric
13th to 15th, 21st, 22nd, Y chromosome
Acrocentric
Centromere is found at the end of chromosome, no p arm exists
Telocentric
T/F: Telocentric chromosomes are sometimes normally found in humans.
False
cancer cells, mice and rodents
Plants that contain telocentric chromosomes
Oxalis - Shamrock
This scientists determined the ratio of p and q arms for each chromosome type.
Levan et al
M/m
Metacentric
1.0-1.6/1.7
Metacentric
Sm
Submetacentric
3.0
Submetacentric
St
Subtelocentric
3.1-6.9
Subtelocentric
T
Acrocentric
7.0
Acrocentric
T, Not applicable
Telocentric
Formula for Arm Ratio
Q arm divided by P arm
T/F: Telomeres and centromeres are only present in eukaryotic cells.
True
This is the tip of each chromosome with tandem repeats of a hexameric sequence.
Telomere
Hexameric sequence, does not code for any information
TTAGGG
Term for the hexameric sequence
Overhang
Nucleotides in telomere
50-400 nucleotides
Where are telomeres often compared to?
aglets of shoelaces
Functions of Telomere
- Preventing abnormal end-to-end fusion of chromosomes
- Protecting the ends of chromosomes from degradation
- Ensuring complete DNA replication
- Having a role in chromosome pairing during meiosis
Function of telomere in early meiosis
anchoring chromosomes to inner membrane, homologous chromosome pairing
T/F: Longer telomeres, longer life span.
True
Found in the end of telomere, lengthens it and has a role in inactivation.
Telomerase
This refers to the limited cellular division.
Hayflick limit / Hayflick model