Genetics Flashcards
Genetic cross
mate (breed) selected individuals to reveal underlying in heritance
Genetics
Scientific study of inheritance
What is special about pea plants?
They can self-fertilize
True-breeding traits
Parents with identical alleles yield offspring with the same allele
Parental Generation
parents that are crossed
1st filial generation (F1)
first generation of offspring
2nd filial generation (F2)
offspring when F1 are bred
What is the ratio of the F2 generation when the P generation are true-bred?
3:1
Genes can be…
dominant or recessive
What are alternative forms of genes?
Alleles
Law of Independent Assortment
different traits are independent of each other (not on the same chromosome)
Incomplete dominance
neither trait is dominant
Co-dominance
traits of both true-breeding parents visible in offspring
What determines phenotype?
Genes + environment
What is the difference between fraternal and identical twins?
fraternal: two eggs
identical: one egg
How many autosomal chromosomes do humans have?
22 non-sec chromosomes
What are some recessive gene defects?
Sickle cell anemia- red blood cells- autosomal
Cystic Fibrosis
Tay-Sachs
If a disease, like Tay Sachs, is autosomal and recessive and both parents are carriers, what percentage of children with inherit the disorder?
25%
What is the difference between dominant gene defects and recessive gene defects?
only need 1 copy (1 allele) of gene of dominant to have the defect, need 2 with recessive
When do symptoms of Huntington’s disease appear?
Mid-life, it is a dominant defect
What is polydactyly?
extra fingers or toes- dominant defect
What is a sex-linked trait?
Gene on sex chromosomes
If a father is colorblind and a mother is normal (XCXc), what percentage of children will be colorblind?
50%
How is hemophilia inherited?
sex-linked recessive
How does a man inherited a sex-linked recessive trait? That is, where specifically does the allele com from?
Mother, dad gives the Y chromosome
What are sex-influenced traits?
autosomal traits in which the phenotype is influenced by sex hormones (environment) –the alleles are not on the sex chromosomes
What is aneuploidy?
Incorrect number of chromosomes
What is non-disjunction?
the cause of aneuploidy- no seperation during either Meiosis 1 or 2, leaving the incorrect number of chrosomes
What is down-syndrome?
Most common aneuploidy- Trisomy 21- extra 21st chromosome
What are some types of abnormal chromosome structures?
Deletion, duplication, translocation- crossing over in non-homologous chromosomes
What does genetic screening do?
Used to diagnose genetic diseases, identify carriers, predict risks
What do we use ultrasounds for?
date pregnancy, confirm viability, determine sex, check for major physical abnormalities, twins, growth rate
What is amniocentesis?
test for genetic abnormalities, hypodermic needle into the water sac
What is chorionic villus sampling? CVS
determining genetic disorders from the placenta
What is ecology?
Study of interrelationships (interactions) of organisms and environment
What is a population?
groups of individuals of the same species in an area
2 properties of populations
genetic makeup can change over time, characteristics (appearance) can also change
Evolution
Change in genetic makeup of population over time
What were Darwin’s believes before and after his trip?
Before: content that species don’t change
after: lineages of organisms gradually change
What were some of Darwin’s conclusions?
individuals variable in population, some variation is passed to offspring (heritable), more offspring are produced than survive, survival and reproduction is not random–natural selection
Natural Selection
individuals with favorable traits produce more offspring in their lifetime than those with less favorable traits and this leads to change
What are the mechanisms of evolution?
Mutations, migration, genetic drift, non-random mating, selection (nat. and art.)
Artificial selection
selection by humans, selective breeding that produces new strains of domestic organisms
What are the types of artificial selection?
Directional, stabilizing, disruptive
Directional selection
favor one extreme phenotype
Stabilizing selection
favors average over both extremes
Disruptive Selection
Favors both extremes, selects against the average
Speciation
Process by which one species becomes two or more
How does speciation occur?
populations are separated via barrier, environments slowly change/diverge, become district and can no longer interbreed
Pre-mating mechanism
Prevents mating- behavioral differences among species make them unnattractive
Post-mating mechanisms
mate not viable, sperm didn’t survive, didn’t fertilize, embryo doesn’t develop, etc.
What is the initial factor in speciation?
Geographic separation
Adaptation
Traits that allow organisms to survive and reproduce
Vestigial Structrures
Structures that have no function for organism today
Genetic engineering
Manipulation of organism’s genetic materials
Steps of genetic engineering
Chop, amplify, insert, grow, identify
BT corn
insect resistant crop
Monohybrid cross
Cross between individuals that differ in only one trait (ex: flower color is purple vs. white)
Test cross
cross to determine genotype of individual with dominant trait
Mendel’s first Law
the 2 alleles carried by each parents are separated during formation of gametes
