Genetic Processes Flashcards
mitosis purpose
The purpose of mitosis is cell regeneration, growth, and asexual reproduction
mitoses stages
Interphase
—cell grows while carrying out normal function
—replication of chromosomes
—DNA is in form of chromatin
Prophase
—DNA condenses and becomes shorted and thicker
—nuclear membrane dissolves
—spindle fibers begin to form
Metaphase
—chromosomes line up in middle of cell with help of spindle fibers attached to centromere of each replicated chromosome (sister chromatids)
Anaphase
—centromeres divide in middle
—sister chromatids puled to opposite sides by spindle fibers
Telophase
—chromosomes reach opposite sides of cell and begin to unwind
—spindle fibers dissolve
—nuclear membrane reforms around chromosomes
Cytokinesis
—splitting of cytoplasm and all organelles into 2 daughter cells
—haploid
meiosis purpose
while the purpose of meiosis is the production of gametes for sexual reproduction.
meiosis stages
interphase
—At the end of interphase chromosomes have replicated
—Chromatin begins to condense
prophase 1
—Chromatin shorten to form chromosomes
—Homologous chromosomes pair up (synapse) to form tetrads
metaphase 1
—Homologous chromosomes line up randomly (in pairs) across equator of cell
—Centromeres of chromosomes attach to spindle fibers
anaphase 1
—Homologous chromosomes separate and move along spindle fibers towards poles of cell
telophase 1
—Cell begins to divide into daughter cells
—Each daughter cell can get any combo of maternal or paternal chromosomes
prophase 2
—Nuclear membrane dissolves
—Spindle fibers begin to form again
metaphase 2
—Chromosomes line up on spindle fibers
—Sister chromatids remain attached at their centromeres
anaphase 2
—centromeres split and sister chromatids separate and move to opposite poles of cell
—Chromatids now called (single stranded) chromosomes
telophase 2
—With the formation of 4 cells, meiosis is over
—Each of these prospective germ cells carry half the number of chromosomes of somatic cells
DNA structure
- -double helix
- -DNA wrapped around histones and coiled tightly to form chromosomes
- -made of repeating subnits called nucleotides
- -4 different bases
- -Adenine —-Thymine
- -Cytosine —-Guanine
- -the sides of DNA ladder are phosphate and sugar held together by hydrogen bonds
Mendel’s Laws
mendel’s law of segregation:
—When sperm and egg unite at fertilization, each contributes its allele, restoring the paired condition in the offspring
—each pair of alleles segregates independently of the other pairs of alleles during gamete formation.
mendel’s law of independent assortment:
—stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.
Monohybrid
- -a hybrid that is heterozygous (one is dominant and one is recessive) with respect to a specified gene.
- -always yields a 3:1 ratio (dominant: recessive)
- -TT x tt
Dihybrid
- -a hybrid that is heterozygous for alleles of two different genes.
- -SsYy x SsYy
Incomplete dominance
- -heterozygous individuals have intermediate phenotype
- -neither of allele is dominant
- -white x red = pink
- (1:2:1= genotype) (red:pink:white= phenotype)
Codominance
- -both alleles completely expressed to produce offspring with third mixed phenotype
- -format similar to incomplete dominance
- -rooster colour
- Black x white= black and white speckled
Multiple Alleles
- -more than 2 alleles for the traits
- -combo of dominant and co dominant genetic traits
- -blood types
- -three blood types alleles: Ia, Ib, i
Sex-linkage
- -phenotypic expression of an allele that is dependent on the gender of the individual and is directly tied to the sex chromosomes.
- -Female = homozygous XX
- -male = heterozygous XY
Pedigrees
- -used to trace inheritance of traits among families
- -normal male =blank square
- -affected male= black square
- -normal female= blank circle
- -affected female= black circle
Mutations
POINT MUTATIONS
–small scale change in nitrogenous base sequence of DNA
–occur witin gene in fixed area
–3 kinds
base pair substitution
insertions
deletions
CHROMOSOME MUTATIONS
–error of entire/large part of chromosome
INHERITANCE OF MUTATIONS
–most mutations occur in DNA that are non-coding
–many mutations correct as replications continues
–occur in somatic cells
INDUCED MUTATIONS
–caused by external, environmental factors
result of chemical/physical agents
TRANSPOSONS
–a small piece of DNA that inserts itself into another place in the genome.
