02 Flashcards
What is a Chromosome?
A Chromosome looks like a thread and is coiled material present in the nucleus of all the cells and contains the basic genetic material DNA, which passes from one generation to another.
What is the microscopic structure of a chromosome?
Chromosome is a microscopic thread-like structure carrying hereditary information in the form of genes.
When are chromosomes visible under a light microscope?
Chromosomes are visible at metaphase stage of mitosis.
Who first described chromosomes, and who coined the term?
Strausberger first described chromosomes in 1875, and the term chromosome was given by Waldeyer in 1888.
What does the somatic chromosome number represent?
The somatic chromosome number is the number of chromosomes present in somatic cells, represented by 2n.
What does the gametic chromosome number represent?
The gametic chromosome number is the number of chromosomes present in gametic cells, represented by n, and is half of the somatic number.
Define homologous chromosomes.
Homologous chromosomes are two copies of a chromosome that are identical in morphology, gene order, and gene content.
What happens to chromosomes during interphase?
During interphase, chromosomes are longest and thinnest and are not visible under a light microscope.
What structural features are seen in metaphase chromosomes?
The following structural features are seen: Chromatid, Centromere, Telomere, Secondary constriction, and Chromomere.
What is a chromatid?
A chromatid is each half of a chromosome joined by a centromere, containing DNA.
What is chromatin?
Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.
What is the function of the centromere?
The centromere enables movement of the chromosome during the anaphase stage of cell division.
What is a telomere?
Telomere is the terminal region of each side of the chromosome that protects DNA from degradation.
What is chromonema?
Chromonema is a threadlike coiled filamentous structure along which chromomeres are arranged.
Define chromomeres.
Chromomeres are bead-like structures present on threads or chromonema, responsible for carrying genes during cell division.
What are the four types of chromosomes based on centromere position?
- Metacentric chromosomes * Submetacentric chromosomes * Acrocentric chromosomes * Telocentric chromosomes
What is a metacentric chromosome?
A metacentric chromosome has the centromere located at the center, resulting in equal arms.
What shape do submetacentric chromosomes appear as during anaphase?
Submetacentric chromosomes appear as either ‘V’ or ‘J’ shaped during anaphase.
What is a polycentric chromosome?
A polycentric chromosome has more than one centromere.
What is heterochromatin?
Heterochromatin is a type of chromatin that takes deep stain during prophase and interphase.
What is euchromatin?
Euchromatin is lightly stained during interphase and deeply stained during metaphase.
What are the primary components of chromosomes?
- DNA * RNA * Protein
What is the nucleosome solenoid model?
The nucleosome solenoid model describes chromatin as consisting of repeating units called nucleosomes.
What does a nucleosome consist of?
- Nucleosome core * Linker DNA * H1 histone * Other chromosomal proteins
What is the role of histones in chromatin?
Histones help in organizing and compacting the DNA into a highly ordered structure, preventing tangling.
How much DNA is contained in metaphase chromosomes?
Metaphase chromosomes contain 15-20% DNA.
What is the diameter of the nucleosome core?
One complete nucleosome has a diameter of 11nm.
What is the jelly-like substance present inside the pellicle?
Matrix is the jelly-like substance present inside the pellicle surrounding each chromosome.
What happens to telomeres during replication cycles?
Telomeres shorten with each replication cycle.
What is a Chromosome?
A Chromosome looks like a thread and is coiled material present in the nucleus of all the cells and contains the basic genetic material DNA, which passes from one generation to another.
What is the microscopic structure of a chromosome?
Chromosome is a microscopic thread-like structure carrying hereditary information in the form of genes.
When are chromosomes visible under a light microscope?
Chromosomes are visible at metaphase stage of mitosis.
Who first described chromosomes, and who coined the term?
Strausberger first described chromosomes in 1875, and the term chromosome was given by Waldeyer in 1888.
What does the somatic chromosome number represent?
The somatic chromosome number is the number of chromosomes present in somatic cells, represented by 2n.
What does the gametic chromosome number represent?
The gametic chromosome number is the number of chromosomes present in gametic cells, represented by n, and is half of the somatic number.
Define homologous chromosomes.
Homologous chromosomes are two copies of a chromosome that are identical in morphology, gene order, and gene content.
What happens to chromosomes during interphase?
During interphase, chromosomes are longest and thinnest and are not visible under a light microscope.
What structural features are seen in metaphase chromosomes?
The following structural features are seen: Chromatid, Centromere, Telomere, Secondary constriction, and Chromomere.
What is a chromatid?
A chromatid is each half of a chromosome joined by a centromere, containing DNA.
What is chromatin?
Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.
What is the function of the centromere?
The centromere enables movement of the chromosome during the anaphase stage of cell division.
What is a telomere?
Telomere is the terminal region of each side of the chromosome that protects DNA from degradation.
What is chromonema?
Chromonema is a threadlike coiled filamentous structure along which chromomeres are arranged.
Define chromomeres.
Chromomeres are bead-like structures present on threads or chromonema, responsible for carrying genes during cell division.
What are the four types of chromosomes based on centromere position?
- Metacentric chromosomes * Submetacentric chromosomes * Acrocentric chromosomes * Telocentric chromosomes
What is a metacentric chromosome?
A metacentric chromosome has the centromere located at the center, resulting in equal arms.
What shape do submetacentric chromosomes appear as during anaphase?
Submetacentric chromosomes appear as either ‘V’ or ‘J’ shaped during anaphase.
What is a polycentric chromosome?
A polycentric chromosome has more than one centromere.
What is heterochromatin?
Heterochromatin is a type of chromatin that takes deep stain during prophase and interphase.
What is euchromatin?
Euchromatin is lightly stained during interphase and deeply stained during metaphase.
What are the primary components of chromosomes?
- DNA * RNA * Protein
What is the nucleosome solenoid model?
The nucleosome solenoid model describes chromatin as consisting of repeating units called nucleosomes.
What does a nucleosome consist of?
- Nucleosome core * Linker DNA * H1 histone * Other chromosomal proteins
What is the role of histones in chromatin?
Histones help in organizing and compacting the DNA into a highly ordered structure, preventing tangling.
How much DNA is contained in metaphase chromosomes?
Metaphase chromosomes contain 15-20% DNA.
What is the diameter of the nucleosome core?
One complete nucleosome has a diameter of 11nm.
What is the jelly-like substance present inside the pellicle?
Matrix is the jelly-like substance present inside the pellicle surrounding each chromosome.
What happens to telomeres during replication cycles?
Telomeres shorten with each replication cycle.
