PP3 Flashcards
due to meiosis during sexual reproduction
genetic shuffling or genetic recombination-
cell division that involves reduction in chromosome number, from diploid to haploid so a parent only passes on ½ of his/her chromosomes to offspring
meiosis
During meiosis, homologous pairs of chromosomes line up & genes switch from 1 chromosome to another before fertilization occurs
crossing over
fusion of 2 haploid gametes (sperm, eggs) to make 1 diploid zygote, each offspring has ½ of his/her chromosomes from each parent so each offspring is from his/her siblings depending on which gametes form the zygote
fertilization
Discovered how genes work by studying genetics in pea plants by cross pollination (pollen from one plant to another) for desired traits= artificial selection
Gregor Mendel: 1857
1 trait is dominant & 1 trait is recessive & there are ONLY 3 genotypes & 2 phenotypes
Mendelian Genetics
given certain parental genotypes it provides representation of genotypes and phenotypes for offspring
punnett square
Since parents only pass on ____ their alleles for each gene they have to their offspring so as discovered by Mendel genetic variation automatically occurs since the offspring will not be identical to their parents or their siblings
half
“TT” “Tt” “tt”
genotype
physical expression ex tall, short
phenotype
used to explain the concepts from previous slide #6 …..Mendel discovered that 2 “alleles for a gene separate into gametes when they are made during meiosis, each gamete receives ONLY 1 of the 2 alleles”
Depending which alleles combine during fertilization, the phenotypes of the offspring are varied from the parents and from each other, so the phenotype output illustrates genetic shuffling/recombination
law of segregation
As discovered by Mendel, when examining 2 traits/genes, “the alleles from the 2 or more different genes separate from one another and segregate independently of one another when gametes are made” and during fertilization, AGAIN illustrating genetic shuffling/recombination of the offspring
Law of independent assortment
means that these inheritance patterns are different from what Mendel found where 1 trait is dominant & 1 is recessive
Non-Mendelian genetics
more than 2 alleles for a trait, allows for more than 3 genotypes & 2 phenotypes of offspring (not just 1 dominant and 1 recessive)
Multiple alleles
Human blood typing alleles-
I A, IB, io
2 of the multiple alleles from slide #9 are equally dominant and both are equally expressed when they are together in a genotype; Allows more than 3 genotypes and 2 phenotypes
Codominance
still 3 genotypes RR, Rr, and rr but
3 phenotypes- RR=dominant red, rr= recessive white, and Rr= intermediate (blended or mixed for heterozygous genotype) so pink
Incomplete dominance
alleles available for offspring in a gene pool can be different for different populations of a species in different locations around the world & can change with
migration
interbreeding members of a species
population
all genes/alleles available in a population for a trait
gene pool
alternative forms of a gene
alleles
movement of individuals from one place to another, can change alleles available, due to gene flow between gene pools
migration
% of an allele in a population
allele frequency
Because of genes available in the gene pool, allele frequency can be different in different locations of the world and at different times, ______ can lead to gene flow between gene pools thus result in changes in allele frequency
migration
discovered transposons in maize and won the Nobel Prize in Physiology or Medicine in 1983 for the discovery
Barbara McClintock
genes that can move from one area of a chromosome to another area of a chromosome, often within another gene, so that they inhibit the expression of those genes (interfere with the protein the gene codes for, thus changes the phenotype for that gene)
Transposons-
makes up genes, genes are found on chromosomes,
and genes code for proteins (gene expression= the protein the gene codes for and the phenotype it causes
DNA
makes mRNA during transcription of protein synthesis, mRNA pairs with tRNA’s during translation of protein synthesis in order to assemble amino acids into a polypeptide and later a protein
DNA
COULD affect or change the mRNA or tRNA as well as amino acids they code for, thus could affect or change the protein produced, but sometimes it does NOT change anything, see why on the next slide
Mutations in DNA
Sometimes multiple mRNA ______ for the same amino acid so sometimes mutations in codons of mRNA (or DNA before it) do not cause changes in amino acids coded for or proteins made
codons
diploid body cells made from mitosis
somatic cells
haploid sex cells made from meiosis
gametes
COULD affect the proteins made by those genes, these mutations could be inherited if they affect many cells in the body due to how they are inherited, and can lead to evolution in a bad way
Mutations in genes in somatic cells
gametes of animals pass on master control genes to offspring that control the development of their body parts in the embryo during development, they are found in stem cells, the same master control genes are found in many animals
All cells of embryo/fetus originate from 1 zygote stem cell that undergoes mitosis (cell division)
All cells begin as undifferentiated cells
Then, the stem cells begin to differentiate and develop specific functions (AKA specialize) due to DNA and genes that are turned on in each cell
Form skin cells, bone cells, brain cells, etc
evo devo
specialized genes that control development of the same body parts in the different animals
Master control genes and Hox genes
same genes found in many animals that control development of same structures/functions in all the animals that have it
Master control genes
examples of master control genes
hox
similar sequences of nucleotides in master control genes of different animals
Homeotic boxes (or homeoboxes)
Same master control genes or Hox genes are found in different animals and they form the same body part in each animal, but the body parts are adapted differently for each animal
ex. all animals have appendages but in humans they are arms and legs, in insects they are legs and wings and the legs look differently in each
yeah
Hox genes exist due to shared _______ ______ of animals during the Cambrian explosion when all animal species underwent divergent evolution, the same master control genes were inherited by all of them
common ancestory
eye development
pax 6
limb
development- antenna, legs, wings
distaless gene
heart
development
tinman
Mutations in ______ can be more serious than in somatic cells especially if they are in master control genes
gamates
mutation in a (ex. distal less- dll) could be dangerous or deadly to offspring
‘master control gene’
Mutations in gametes and master control genes are always _____ and thus can lead to evolution (in a good or bad way depending on the mutation and its effect)
inherited
