Genetics Flashcards
What is cell division
When a cell makes a genetically identical copy of itself
Why do cells divide?
To grow, repair tissue and develop or change
What are homologous chromosomes?
Pairs of chromosomes that carry corresponding DNA. One member of each pair comes from male and female
Explain what diploid sand haploid are
D: the number of chromosomes (2N) found in each cell of a given species. Includes homologous pairs.
H: the number of unpaired chromosomes (N) found in an egg or sperm cell
How much is each stage of the cell cycle
90% interphase, 10% mitosis
What are chromatin
DNA and protein. The state of chromosomes during interphase
Explain interphase
Strands of DNA separate, creating an exact copy of itself. Now referred to as sister chromatids which are joined by a centromere.
Go through stages of interphase
G1 phase: cytoplasm and organelles are produced
S phase: synthesis, DNA replicates
G2: remakes materials used in s phase. Now in 4N stage
Explain each stage of mitosis
Prophase: chromosomes become visible when chromatin shortens and thickens. Chromatid pairs form.
Metaphase: chromatid pairs line up in centre of cell.
Anaphase: pairs separate
Telophase: cytoplasm Serpentes and two nuclei form.
Explain mitosis 1 of meiosis
Prophase I: chromatin shortens and thickens to become visible. Synapsis (crossing over) occurs. Homologous pairs sort together.
Metaphase I: chromosomes in tetrads line up on equator of cell. Nuclear membrane is gone and spindle fibres have been formed.
Anaphase I: homologous pairs break up into separate double strand chromosomes.
Telophase I: nuclei reassembled. Cytoplasm divides.
Explain mitosis II of meiosis.
Prophase II: homologous pairs organize
Metaphase II: homologous pairs line up in centre
Anaphase II: chromatids divide in half
Telophase II: nuclei reform and cytoplasm divides. N stage is formed and interphase begins again.
Explain the law of independent assortment.
The direction in which maternal and paternal chromosomes migrate is random. Creates variation.
Explain synapsis.
Non-sister chromatids break and rejoin, exchanging DNA segments. The resulting chromosome will have DNA from both maternal and paternal chromosomes. Creates variation.
What is nondisjunction?
when homologous chromosomes do not
separate correctly in anaphase I (or when sister chromatids do not separate correctly in anaphase II)
This results in some gametes having too many chromosomes and some gametes having too few chromosomes
What is trisomy and monosomy?
Trisomy: having an extra chromosome
Monosomy: having one less chromosome
Explain Down syndrome.
Trisomy of chromosome 21. Characterized by intellectual disabilities and almond shaped eyes.
Give examples of sex-linked traits.
- colour blindness
- hemophilia
- male-pattern baldness
- hairy pinna
Explain incomplete dominance and co-dominance
Incomplete: one allele doesn’t dominate over another allele completely, creating a new phenotype. Example: red and white forming pink.
Co-dominance: alleles in a heterozygote are both fully expressed
Define alleles.
A variant of a gene. Can have different phenotypic expression. Example: gene for eye colour can have an allele for brown or blue.
What are hybrids?
Offspring of parents that differ in genetically determined traits.
What is a pedigree
Diagram that shows the lineage of a family and its genealogy.
What is the universal blood donor type? Recipient? Why?
Donor: O is compatibility with any blood type. Has no anti b or anti a reactions.
Recipient: AB. Can receive any blood type, as it contains no antibodies.
How can we determine our blood type using antigens?
Our blood produces antigens of our blood type. If you produce A antibodies, you have type A blood. B is B, A and B is Ab and none is O.
What happens if you receive a transfusion of the wrong blood type?
Your body produces anti bodies against any blood types that aren’t yours. If you receive the wrong blood type, your immune system will attack the new blood cells, destroying them and not allowing you to receive enough blood.
What are antibodies? Antigens?
Antibodies work in the immune system to counter antigens. Antigens are foreign substances that create an immune response in the body.
