[MT] CHROMOSOME STRUCTURE

Located at the tip of the chromosome.

Telomere

Non-coding region composed of multiple repeats of TTAGGG.

Telomere

Associated with aging and cell senescence.

Telomere

The point where a cell stops dividing because its DNA can no longer replicate.

Cell Senescence

Shortens after every replication until it reaches a critical limit where the cell can no longer divide.

Telomere

The maximum number of times a normal human cell can divide before stopping.

Hayflick Limit

Located in the middle of the chromosome (largest constriction).

Centromere

Facilitates the attachment of sister chromatids.

Centromere

Spindle fibers attach here when chromatids separate.

Centromere

Composed of 171 base-pair DNA sequence repeats.

Centromere

Replicates during the S phase of the cell cycle.

Centromere

Tightly packed, highly condensed chromatin.

Heterochromatin

Stains dark under microscopy.

Heterochromatin

Genetically inactive; contains few or no genes.

Heterochromatin

Provides structural integrity to the chromosome.

Heterochromatin

Always condensed and contains repetitive DNA sequences.

Constitutive Heterochromatin

Can switch between condensed and decondensed forms.

Facultative Heterochromatin

Example of gene expression switching through chromatin change.

Facultative Heterochromatin

Loosely packed, less condensed chromatin.

Euchromatin

Lighter staining under microscopy.

Euchromatin

Genetically active; contains frequently transcribed genes.

Euchromatin

Contains the Origin of Replication and Promoter Region.

Euchromatin

What is the counterpart of the origin of replication in transcription?

Promoter Region

Centromere located at the end of the chromosome.

Telocentric Chromosome

Important note: Not present in humans.

Telocentric Chromosome

Centromere located very near the end of the chromosome.

Acrocentric Chromosome

Has a very short p arm and a long q arm.

Acrocentric Chromosome

Humans have specific chromosomes of this type.

Acrocentric Chromosome

Found between the telomere and the gene-rich region of the chromosome.

Subtelomere

Maintains and regulates telomere function.

Subtelomere

Plays a role in chromosome organization and stability.

Subtelomere

Responsible for DNA variability due to repetitive sequences and rearrangements.

Subtelomere

Centromere is located at the end of the chromosome.

Telocentric Chromosome

Has only one visible chromosome arm.

Telocentric Chromosome

Not present in humans.

Telocentric Chromosome

Centromere is very near the end of the chromosome.

Acrocentric Chromosome

Has a very short P arm and a long Q arm.

Acrocentric Chromosome

Usually contains satellites.

Acrocentric Chromosome

Humans have this type of chromosome.

Acrocentric Chromosome

Centromere is off-center.

Submetacentric Chromosome

Has a short P arm and a long Q arm.

Submetacentric Chromosome

P stands for.

Petit

Q is the long arm, chosen because it follows P in the alphabet.

Submetacentric Chromosome

Centromere is exactly at the center.

Metacentric Chromosome

Both arms are of equal length.

Metacentric Chromosome

X-shaped in appearance.

Metacentric Chromosome