Bio Exam Study Flashcards
(9 cards)
Distinguish between DNA, genes, and Chromosomes.
DNA is responsible for maintaining and building human structure, Chromosomes carry DNA, and genes are segments of our DNA that make up our appearance.
Difference between Autosomes and Sex Chromosomes
Autosomes are chromosomes that determine the body’s general traits, while sex chromosomes determine an individual’s sex.
Indentifying males and females based on a karyotype
Karyotypes for a female contain two X chromosomes and are denoted for the sex XX. Males usually have both an X and a Y chromosome, denoted for the sex XY.
Identifying chromosomal abornamlites from a karyotype
See whether you have a full set of 46 chromosomes. Having too many or too few chromosomes can cause serious problems with health, growth, and normal development, such as Down syndrome (extra chromosome 21) and Turner syndrome (missing X chromosome).
Nature of a pair of homologous chromosomes as carrying the same gene loci.
The two chromosomes in a homologous pair are very similar to one another and have the same size and shape. Most importantly, they carry the same type of genetic information: that is, they have the same genes in the same locations. However, they don’t necessarily have the same versions of genes.
Stages of Meiosis
Prophase 1: DNA condenses, nucleus breaks down, homologous pairs find each other, sister chromatids cross over and create recombinant chromosomes.
Metaphase 1: Homologous pairs line up in the centre of the cell, spindle fibres from each end of the cell connect to one centromere from each pair.
Anaphase 1: Homologous chromosome pairs are separated + move to opposite sides of the cell.
Telophase 1: Gather at the poles of the cell, new cytokinesis divides.
Prophase 2: New spindles form around the chromosomes
Metaphase 2: Chromosomes line up in the middle
Anaphase 2: Centromeres divide, chromatids move to opposite sides.
Telophase 2: Nucleus forms and cell divides into now 4 daughter cells
Difference between Meiosis and Mitosis
Mitosis produces two genetically identical “daughter” cells from a single “parent” cell, whereas meiosis produces cells that are genetically unique from the parent and contain only half as much DNA.
How Meiosis results in increased genetic diversity
Specifically, meiosis creates new combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes. Such exchange means that the gametes produced through meiosis exhibit an amazing range of genetic variation.
