18 Questions
What is the structure that forms when nucleosomes are linked by the H1 histone protein?
Chromatosomes
What is the name of the constriction point that divides a chromosome into two sections or 'arms'?
Centromere
What is the shorter section of a chromosome called, and what is the longer section called?
The shorter section is designated the p arm, and the longer section is designated the q arm.
What is the role of the centromere during cell division?
Centromeres act as a point of attachment for spindle fibres during cell division.
How can different chromosomes in a eukaryotic species be distinguished?
Chromosomes can be distinguished by their size and the location of the centromere.
What is the term used to describe the position of a particular gene on a chromosome?
The locus
What is the purpose of karyotyping?
Karyotyping is used to organize chromosomes of a cell in relation to number, size, and type in order to determine the sex of the fetus and diagnose chromosomal abnormalities such as Down syndrome.
What is the difference between haploid and diploid cells?
Haploid cells contain a single set of chromosomes, while diploid cells contain two complete sets of chromosomes.
What is the role of alleles in genetic information?
Alleles are different forms of the same gene that occupy the same locus on homologous chromosomes. Alleles determine the expression of specific traits.
Explain the significance of homologous chromosomes.
Homologous chromosomes are a pair of chromosomes that contain the same genes in the same order, but may have different alleles for each gene.
What is the role of histones in the structure of DNA?
Histones are proteins that DNA wraps around to form nucleosomes, which are the basic units of chromatin. Histones help to compact and organize the DNA within the cell nucleus.
Describe the process of DNA sequencing using autoradiography.
DNA sequencing using autoradiography involves labeling DNA fragments with radioactive nucleotides, separating the fragments by size, and exposing them to X-ray film to create a banding pattern that can be used to determine the DNA sequence.
Explain the fundamental difference between haploid and diploid cells in terms of their chromosomal composition.
Haploid cells contain one set of chromosomes (n), while diploid cells contain two sets of chromosomes (2n).
In humans, what is the chromosome number for a haploid cell and a diploid somatic cell?
A haploid human cell has 23 chromosomes, while a diploid human somatic cell has 46 chromosomes (23 homologous pairs).
What is the primary function of haploid cells in the context of genetic inheritance?
The primary function of haploid cells (gametes) is to provide half of the genetic information to the offspring generation (zygote) during sexual reproduction.
Differentiate between homologous and non-homologous chromosomes in the context of haploid cells.
In haploid cells, the chromosomes are non-homologous, meaning they are not paired and do not carry the same genetic information. In diploid cells, the chromosomes are homologous, meaning they are paired and carry the same genetic information.
What is the process by which new alleles (alternative forms of a gene) are formed? Provide a brief explanation.
New alleles are formed through mutations, which are changes in the DNA sequence of a gene. Mutations can occur spontaneously or be induced by various factors, leading to variations in the genetic code and resulting in different alleles.
Explain the term 'gene' and its relationship to alleles and the expression of specific characteristics.
A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic. Alleles are the various specific forms of a gene, and they can result in different expressions or variations of the characteristic controlled by that gene.
Study Notes
Karyotyping
- Karyotyping is a method used to organize chromosomes in a cell based on number, size, and type.
- A karyogram is the resulting image depicting homologous pairs in decreasing length.
Use of Karyograms
- Karyograms are used to deduce sex and diagnose Down syndrome in humans.
- Karyotyping occurs prenatally to determine the sex of the fetus and test for chromosomal abnormalities.
Chromosome Structure
- Chromosomes have a constriction point called a centromere, which divides the chromosome into two sections (or ‘arms’).
- The shorter section is designated the p arm, and the longer section is designated the q arm.
- The position of the centromere varies amongst different chromosomes, giving each a characteristic shape.
Identifying Genes
- In eukaryotic species, each chromosome carries specific genes, and the position of a particular gene on a chromosome is called the locus.
- Chromosomes can be distinguished by their size and the location of the centromere.
- Different chromosomes carry different genes.
Haploid and Diploid Cells
- Haploid cells have one copy of each chromosome, providing half of the genetic information to the offspring generation (zygote).
- Diploid cells have two copies of each chromosome, with 23 homologous pairs in humans.
- In humans, somatic cells are diploid (46 chromosomes), while gamete cells are haploid (23 chromosomes).
Terminology
- Allele: a variant of a gene
- Gene: a segment of DNA that carries information to build a protein
- Locus: the position of a particular gene on a chromosome
- Autoradiography: a technique used to visualize the location of radioactive DNA or RNA molecules
- Genome: the complete set of genetic information contained within an organism
- Naked DNA: DNA that is not complexed with histone proteins
- Autosomes: non-sex chromosomes
- Homologous chromosomes: chromosomes that have the same genes in the same order
- Sex chromosomes: chromosomes that determine the sex of an organism
- Centrosome: a region near the centromere where spindle fibers attach during cell division
- Chromatin: the material that makes up chromosomes, composed of DNA and histone proteins
- Nucleosome: a complex of DNA wrapped around eight histone proteins
- Chromatosome: a string of nucleosomes linked by histone protein H1
- Solenoid: a coiled structure of chromatosomes
- Karyotype: the complete set of chromosomes in a cell
Test your knowledge on haploid and diploid cells, focusing on the differences between the two types of cells, their genetic information, and their functions in the body. Explore the concepts related to chromosomes, homologous pairs, and the genetic information passed on to offspring.
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