Genetics Flashcards
What happens in metaphase I?
Tetrads migrate to the centre and more genetic dissimilarities are made by random assortment, how pairs line up across the centre of the cell.
Summarize co-dominance inheritance.
It involves two alleles, 3 genotypes (ex. BB, BW, WW), and 3 phenotypes (black, black and white, white). Two dominant traits combine to form a mixture of the two alleles, very similar to incomplete dominance.
Ex. If a black cow is crossed with a white cow, the offspring will be black and white.
What is a mutation?
The changing of the structure of a gene.
What is a True Breeding Organism?
An organism that produces offspring that are genetically identical for one or more traits.
What is the difference between mitosis and meiosis II?
Four haploid are formed in meiosis II, and two diploid cells are formed in mitosis.
What type of cells are involved in meiosis and mitosis?
Somatic cells (body cells) are involved in mitosis, and gametes (sex cells) are involved in meiosis.
What accounts for the differences between egg and sperm cells?
Eggs must be larger so they can contain more nutrients in their cytoplasm needed for cell division, and as the sperm cells need to be able to swim to an egg to fertilize it, so they must be plentiful, small and fast.
How is genetic variation in the gametes achieved during meiosis?
By crossing over and random assortment.
What happens in the interphase stage of the cell cycle?
DNA replicates and cells prepare for division.
What are homologous chromosomes?
A pair of chromosomes (one from each parent) that contain the same genes at the same locations, but can have different forms of that gene.
When does Down Syndrome occur?
When a male or female has 3 copies of chromosome #21 (trisomy non-disjunction).
What happens in prophase I?
Chromosomes shorten and thicken, nuclear membrane dissolves, homologous chromosomes pair up forming tetrads, and chromosomes exchange DNA in a process called crossing over.
Molecules that have the ability to cut DNA at a specific site are called _________________.
Restriction enzymes
Gametogenesis produces sex cells with half the number of chromosomes as a body cell.
True
Define hybrid.
A hybrid is an offspring resulting from the cross between two true-breeding species.
Explain crossing over.
Crossing over occurs when the tetrad of homologous chromosome tangle and exchange pieces of DNA in prophase 1.
Less than ___% of the total genome codes for protein.
2%
Describe sex-linked inheritance in regards to hemophilia.
As the hemophilia allele is passed on in the X chromosome, females can be normal, a carrier or a hemophiliac (XHXH, XHXh, XhXh). As males only have one X chromosome, they are either normal or hemophiliacs (XHY, XhY).
State the difference between monosomy and trisomy non-disjunction?
Trisomy is when there is three homologous chromosomes in the place of a homologous pair, and monosomy is when their is one chromosome in place of a homologous pair.
How many cells are produced from one cycle of meiosis and mitosis?
4 cells are produced from meiosis, and 2 from mitosis.
Define diploid.
Containing a set of chromosomes, one from each parent.
What is the role of the resulting cells from meiosis and mitosis?
Cells resulting from mitosis are the same as the parent cell, and used to create more somatic cells. Cells resulting from meiosis are used to create sex cells for reproduction.
What is the difference between discontinuous and continuous variation?
Discontinuous variation is when the inheritance of one gene has no effect on the expression of products of the second gene, and continuous variation is when a phenotype is determined by the interaction of different genes together (ie. skin colour).
Define allele.
A particular type of gene (ie. allele for eye colour, hair, etc.)
State the Principal of Dominance.
When individuals with contrasting traits are crossed, the offspring will only express the dominant trait.
What are three reasons for cell division?
Tissue repair, replacing dead cells, and growth.
What is the chromosome number of a parent cell in mitosis and meiosis?
They are both diploid (2n)
What is the function of the cell membrane? [3]
It supports the cell, protects the interior, and controls which substances enter the cell.
Functions unknown for more than ___% of the genes discovered.
50%
What can a karyotype reveal?
Genetic abnormalities in genes of parents or of child with an unknown disability, the gender of a fetus, and test for certain defects through examination of cells from uterine fluid.
What is a chromatin?
An uncoiled strand of DNA
What is the difference between genetics and genomics?
Genetics is the study of single genes in isolation and genomics is the study of all genes in the genome and the interactions among them and their environment[s] (or the study of the genome in an organism).
What is DNA fingerprinting?
The technique of analyzing DNA fragments. Those fragments form distinct patterns that can be used to identify a person or organism.
Summarize incomplete dominance inheritance.
It involves two alleles, 3 possible genotypes (ex. CRR, CWW, CRW), and 3 possible phenotypes (ex. red, pink, white). Two dominant traits combine to form an entirely different trait in the offspring, very similar to co-dominance.
Ex. If a red flower is crossed with a white flower, the subsequent offspring will be pink.
Explain random assortment.
Random assortment occurs when tetrads of homologous chromosomes migrate to the center of a cell and randomly align across the middle in metaphase 1.
How many chromosomes do human body cells usually contain?
46 (23 pairs)
What some characteristics of all living things? [8]
Require energy, composed of cells, able to reproduce, require water, respiration, produce waste, growth, able to adapt to environment.
What is the Human Genome Project?
A project began in 1990 and completed in 2004 mapping the DNA sequence of the entire human genome.
What happens in telophase I?
A nuclear membrane reforms around the new nuclei.
