Genetics and Inheritance Flashcards
the study of heredity
Genetics
characteristics passed from parents to their offspring
Heredity
What are 3 things that can be hereditary? Give examples
- Physical Characteristics - coat color
- Behavioral Traits - temperament
- Medical Conditions - hipdysplasia
inherited from each parent, contain DNA, and make cell division and replication easier
Chromosomes
What are the 2 ways you can write Chromosomes?
- Total # of individual chromosomes
- Total # of pairs of chromosomes
How many chromosomes do humans have? Pairs vs Individual
23 pairs
46 individual
How many chromosomes do canines have? Pairs vs Individual
39 pairs
78 individual
How many chromosomes do felines have? Pairs vs Individual
19 pairs
38 individual
How many chromosomes do horses have? Pairs vs Individual
32 pairs
64 individual
How many chromosomes do cattle have? Pairs vs Individual
30 pairs
60 individual
stretches of DNA that are specific to a particular traits or characteristic
Genes
all of the genes of an organism
Genome
parts of a gene that code for specific traits and control how the gene is expressed
Alleles
How many alleles do you get from each parent per trait?
1 allele from each parent per trait = 2 total per trait
2 complementary, twisted strands of genetic info coiled into spirals
Double Helix (Twister Ladder Shape)
What was the goal of Mendel’s experiment?
To determine if there’s a pattern of how future generations inherit those characteristics
What subjects did Mendel use in his experiments and why?
Common garden pea plants because they are easy to grow in large numbers
What were the 7 plant characteristics that Mendel studied in his experiment? Why did he choose these?
- Flower color
- Flower position
- Plant height
- Seed Color
- Seed Shape
- Pod Color
- Pod Shape
All of these characteristics have 2 trait variants in pea plants
Describe the 5 step procedure Mendel used for is experiment
- Studied 7 characters that each had 2 traits in garden pea plants
- Created purebred strains by cross-breeding different varieties of purebred pea plants > True-bred strains are homozygous for a given trait
- Collected and grew the seeds of the purebred strains to determine their characteristics
- Crossed 2 different purebred strains with particular traits > Allowed him to see how the heterozygous offspring would differ from the purebred strains
- Observed the resulting traits in the offspring pea plants
the mating and production of offspring of living organisms such as plants and animals
Breeding
organisms that can pass on certain traits to all of their offspring
True-Breeding
a type of breeding in which different species or varieties are mated with each other to product a hybrid
Crossbreeding
What is an example of Crossbreeding?
Crossing a tall plant with a short plant
What is an example of True-Breeding?
Green pea pods crossed that always produce green pea pods
the act of transferring _____ from the male part of the plant to the female part of the plant
Pollination
contain the genetic information needed to produce a new plant
Plant Seeds
What does pollination do?
Fertilizes the plant and enables it to make seeds
the offspring of 2 genetically distinct parent species that contain features of both parents
Hybrid
the true-bred parents
P Generation
the first generation of hybrid offspring from individuals in the P generation
F1 Generation
What are 2 characteristics of F1 generations?
- Often displays the dominant gene
- Often heterozygous
the gene that controls the trait
Dominant Gene
the generation of offspring from individuals in the F1 generation
F2 Generation
What are 2 characteristics of F2 generations?
- Often show the effects of hybridization
- Often 50% are heterozygous, 25% are homozygous dominant and 25% are homozygous recessive
a organism’s set of observable characteristics that result from its genetic composition and is sometimes influenced by environmental factors
Phenotype
the variants of a gene an organism contains in their genetic composition that gives rise to the physical expression of characteristics
Genotype
a trait that has 2 copies of the same allele for a given gene
Homozygous
a trait that has 2 different alleles for a given gene
Heterozygous
What are Mendel’s 3 Laws?
- The Law of Segregation
- The Law of Independent Assortment
- The Law of Dominance
What do Mendel’s Laws dictate?
How traits are inherited between generations
The law that states every organism acquires 2 alleles for each trait, with 1 coming from each parent
The Law of Segregation
Where does The Law of Segregation get its name from?
the alleles segregate (separate) during reproduction > each parent contributes only 1 of its 2 alleles for any given trait > seemingly random fashion
the law that states the separation of alleles for a given gene occurs independently of any other gene
The Law of Independent Assortment
When does The Law of Independent Assortment occur?
During meiosis
What is an example of The Law of Independent Assortment?
Whether a plant inherits an allele for purple or white flowers > no effect on the genes it inherits for pea texture
What is the exception to The Law of Independent Assortment?
Linked Genes
genes located on the same chromosome that tend to be inherited together
Linked Genes
The law that establishes which of the 2 inherited genes for a particular trait manifests in an offspring
The Law of Dominance
a gene that will always be completely expressed if it’s present in the organism’s genetic code, even if only 1 parent contributed a this type of allele
Dominant Allele
a gene that will only be completely expressed if both parents contributed this type of allele
Recessive Allele
What is the dominance order for the following eye colors?
Blue Brown Green
Brown > Green > Blue
Brown is dominant
Green is recessive, but dominant to blue
Blue is recessive to both
a chart that shows the different ways alleles from 2 parents can combine and be passed on to offspring
Punnett Square
What can Punnett Squares be used to determine?
The probability of characteristic expression in offspring
What are the 2 types of crosses you can study using a Punnett Square?
- Monohybrid Cross
- Dihybrid Cross
a genetic condition that progressively affects the retina until the feline is completely blind
Progressive Retinal Atrophy (PRA-b)
What cat breed is PRA-b commonly seen in?
Bengal Cats
If a patient comes in with PRA-b, what 3 steps should you take when handling the animal?
- Talk softly in soothing tone > lets them know you’re there
- Allowing them to smell you before introducing physical contact
- Move more slowly with them
shows the independent assortment of alleles for 2 different genes
Dihybrid Cross
What is an example of a dihybrid cross?
Shape and Color of Peas
On a Punnett Square, which sides are the male vs female genotypes listed?
Male - Left
Female - Top
What are 3 exceptions to Mendel’s Principles (besides Linked Genes)?
- Incomplete Dominance
- Codominance
- Environmental Factors
one phenotype does not prevail over the other and instead there’s an intermediate phenotype that’s a mix of both parents’ phenotypes for a given trait
Incomplete Dominance
What are 2 examples of Incomplete Dominance expression?
- Andalusian Chickens: 1 black parent + 1 white parent > can result in a slate gray offspring
- Palomino Horses - 1 cream colored parent + a chestnut parent > can result in a golden blond offspring
What type of coloring do you normally see in offspring expressing incomplete dominance?
Offspring’s color is between the parents’ colors
both recessive and dominant traits are expressed together in an organism’s phenotype on different parts of the animal
Codominance
What are 2 examples of Codominance expression?
- Holstein Cows - 1 black coloring allele + 1 white coloring allele > black and white spots expressed on different parts of the cow
- Chickens - 1 black parent + 1 white parent > can result in black + white speckles
What type of coloring do you normally see in offspring expressing codominance?
pattern that shows both genes in speckles or patches
Which allele is considered dominant in the Holstein Cows example?
Neither - both the black and white alleles are considered dominant
how the external world an organism lives or develops in affects it
Environmental Factors
How can environmental factors be an exception to Mendel’s Principles?
A homozygous recessive organism may not survive its environment and won’t reproduce
Dominant genes will predominate because there are fewer organisms with recessive genes in the population
a coat pattern with fully pigmented hair and diluted color patches with tan or rust-colored markings and brown or blue eyes
Merle (Dapple)
Dapple coats are an example of what kind of dominance?
Incomplete Dominance
merle coat pattern that can display patches of white
Double Merle (Double Dapple)
coat pattern that is white with colored specks and patches
Piebald
What can alert you to possible health concerns in certain animals?
Coat Pattern
What are 2 (of many) dog breeds that can have merle coat patterns?
- Dachshunds
- Australian Shepherd
Double Dapple patients have an increased risk of what 2 things?
Inherited pathology of their:
1. Eyes
2. Ears
Nearly all white double merle patients are at an even higher risk of what 3 things?
- Skeletal Abnormalities
- Reproductive Abnormalities
- Heart Abnormalities
Piebald Coats are an example of what type of dominance pattern?
Codominance
Which coat pattern resembles a double merle but does not carry the risk of genetic abnormalities?
Piebald
Why can’t you assume every dachshund patient with white markings is a double dapple?
Piebald coats look similar to them