True or False: The centromere is always located in the middle of the chromosome.
FALSE
The centromere can be located at different positions on chromosomes.
What is the function of centromeres?
Promote assembly of the kinetochore complex
Centromeres are crucial for equal genome transmission to daughter cells.
What is the end-replication problem associated with linear chromosomes?
Loss of DNA at chromosome ends during replication
This problem is addressed by telomerase in eukaryotic cells.
What are the three parts required for linear chromosomes to function?
- Origins of replication
- Telomeres
- Centromeres
These components are essential for proper chromosome function.
What is the approximate size of the human genome?
3.2 billion base pairs
This size allows for the encoding of approximately 20,000 genes.
How many proteins could be encoded in 3.2 billion base pairs if each protein requires 1500 nucleotides?
2,133,000
This calculation shows the potential protein coding capacity of the human genome.
What percentage of the human genome encodes proteins?
< 2%
The majority of the genome consists of non-coding regions.
What fraction of the human genome is repetitive?
55%
This includes both tandem and interspersed repeats.
What are the two types of repeats found in the human genome?
- Tandem repeats
- Interspersed repeats
These repeats play various roles in genome structure and function.
What are Short Sequence Repeats (SSRs) also known as?
Short Tandem Repeats (STRs)
SSRs are typically 2-5 base pairs in length.
What are Variable Number Tandem Repeats (VNTRs)?
Repeats of 15-100 base pairs in length
VNTRs are a type of tandem repeat found in the genome.
What is the typical length of Long Interspersed Elements (LINEs)?
300 bp to 6,000 bp
Most LINEs are approximately 300 bp in length.
What is the typical length of Short Interspersed Elements (SINEs)?
100-300 bp
SINEs are another type of interspersed repeat in the genome.
What is the bacterial solution to the end-replication problem?
Circular chromosomes
Bacteria have a single circular chromosome that does not have ends.
What is the eukaryotic solution to the end-replication problem?
Telomerase extends 3’ ends
This enzyme helps maintain chromosome integrity during replication.
What is the function of the kinetochore?
Attachment site for spindle microtubules
Kinetochores are essential for proper chromosome segregation during cell division.
What happens if there is more than one centromere per chromosome?
It can lead to improper segregation during mitosis
This can result in aneuploidy or other chromosomal abnormalities.
What is a holocentric chromosome?
A chromosome with kinetochores along its entire length
This allows for proper segregation during mitosis in certain species.
What are the two types of chromosomes based on their structure?
- Circular
- Linear
Circular chromosomes are found in prokaryotes and some organelles, while linear chromosomes are characteristic of eukaryotes.
In which organisms would you find circular chromosomes?
- Prokaryotes (Bacteria)
- Archaea (Archebacteria)
Circular chromosomes are typically found in prokaryotic organisms.
In which organisms would you find linear chromosomes?
- Eukaryote (Organellar)
- Eukaryote (Genomic)
Linear chromosomes are characteristic of eukaryotic organisms.
How is bacterial DNA packaged?
- Loosely condensed
- Compacted into a nucleoid
- Supercoiling
Bacterial DNA is compacted using histone-like proteins and supercoiling.
What is the compaction ratio of eukaryotic DNA in metaphase?
10,000x
This high level of compaction is necessary to fit DNA into the nucleus.
What are the two forms of chromatin observed in eukaryotic cells?
- 11 nm wide (Beads-on-a-string)
- 30 nm wide (Zigzag or Solenoid)
These forms represent different levels of chromatin packaging.
