Unit 5 - Heredity Flashcards
Gametes
- a sex cell ( sperm or an egg)
- designated by the n number
What are gametes made by?
meiosis
Gametogenesis
the process in which cells undergo meiosis to make sex cells
Haploid Number
n - number of chromosomes
Oocyte
egg cell
Fertilization
- sperm and egg meet (sperm enters egg)
- restores the diploid number (2n) bc two haploid gametes each containing half the number of chromosomes (the haploid number), combine to form a diploid.
Diploid
- a number of chromosomes in in a body cell
- 2n
Body cells
somatic cells - autosomes
autosomes
are the chromosomes that determine traits other than sex (e.g., eye color, height, metabolism).
Somatic Cells
are all the cells in your body except gametes (sperm and egg cells).
Karyotype
picture of the chromosomes
Homologous Chromosomes
separate chromosomes (NOT DUPLICATED CHROMOSOMES) that code for the same type of genes (ex. height )
- inherited
Mitosis
produces 2 genetically identical cells
Meiosis
produces gametes ( provides variety )
Interphase (part of S-phase)
- start with 6 chromosomes and duplicate the chromosomes
- in the end we should have 4 haploid cells with half chromosomes in each so 3 in each
Meiosis 1 ( the first division )
Prophase 1
- chromosomes condense
- homologous chromosomes pair up (one from dad and one from mom)
- recombination of genes (when they pair up they combine to make tetrad and chiasma
Synapsis in Prophase 1
when the homologous chromosomes pair up (one from dad and one from mom)
Tetrad in Prophase 1
is created when two homologous chromosomes (one from each parent) pair up.
Each chromosome in the pair has two identical sister chromatids. Together, that makes 4 chromatids total, hence the name “tetrad.”
Chiasma
physical site where homologous chromosomes overlap and swap DNA. So this is where they are touching and where they recombine to get that variety
Meiosis 1
Metaphase 1
the homologous chromosomes line up
Law Of Independent Assortment
chromosomes can line up in many different arrangements
Meiosis 1
Anaphase 1
- homologous chromosomes separate
- if chromosomes don’t separate correctly then you have non-disjunction which is uneven distribution of chromosomes
Meiosis 1
Telophase 1
two haploid cells are made and they are genetically different
Why do the chromosomes go straight to prophase and not to interphase when you go to meiosis 2?
After Meiosis I, the sister chromatids are already present, so there’s no need to replicate the DNA again before Meiosis II.
Meiosis 2
Prophase 2
nuclear envelope breaks down
Meiosis 2
Metaphase 2
chromosomes line up
Meiosis 2
Anaphase 2
the sister chromatids pull apart
Meiosis 2
Telophase and Cytokinesis
both cells divide again, making four unique haploid cells.
and now we make sex cells so 4x sperm, 1x egg, and 3x polar bodies that are useless
polar bodies
small non-usable cells that do not fertilize and they get reabsorbed into the body
Law Of Segregation
genes that go into gametes sort randomly and this allows for variety
Autosomal Inheritance
inherit 2 of every kind
Phenotype
observable characteristics so what protein is being made and expressed
Genotype
actual gene that codes for a protein to express phenotype
Allele
- different forms of a gene
- ex. you receive brown hair from mom and blond hair from dad
How does genotype determine phenotype
genotypes code for the production of a protein and that protein gives our physical traits
Homozygous dominant
An individual has two dominant alleles for a gene (e.g., AA).
Heterozygous
An individual has one dominant allele and one recessive allele for a gene (e.g., Aa).
Homozygous recessive
An individual has two recessive alleles for a gene (e.g., aa).
Locus
specific location of a gene
On the genetic level what is happening?
- gene codes for a protein
- gene gets transcribed into mRNA
- mRNA goes to the ribosomes to make a protein
Homozygous dominant (true breeding)
Two dominant alleles for a trait (AA).
Always passes on the dominant allele to offspring.
Homozygous recessive (true breeding):
Two recessive alleles for a trait (aa).
Always passes on the recessive allele to offspring.
Heterozygous (hybrid):
One dominant and one recessive allele for a trait (Aa).
Displays the dominant trait but can pass on either allele to offspring.
Carrier
A heterozygous individual for a recessive trait (Aa) that does not express the recessive condition but can pass the recessive allele to offspring.
Wild Type
the original/ natural form of a gene
Blood Clotting
- original form: blood clotted and clot broke down
- mutated: blood clots and clots and clots
Phenotypic ratio
9:3:3:1
What happens to chromosome numbers in both meiosis 1 and meiosis 2?
The number of chromosomes in a cell is halved during meiosis I and maintained during meiosis II
Imcomplete Dominance
neither allele is dominant over the other so its the blending of allele resulting in a new phenotype
Co dominance
both alleles are expressed in the heterozygous condition
Polygenic Inheritance
multiple genes that will code for one specific phenotype
Epistasis
multiple genes that code for a phenotype and one gene that modifies/controls phenotype
Linked Traits
genes found on the same chromosome
Epistasis
multiple genes that code for a phenotype and one gene that modifies/controls phenotype
If genes are located on different chromosomes what does that mean
it means they assort independently and u expect a 1:1:1:1 ratio
