Genetics Flashcards
Genetics definition
The scientific study of heredity
Heredity definition
The transmission of trait from one generation to the next.
Who was the first person to analyze patterns of inheritance?
G. Mendel
Why did G Mendel study garden peas?
They were easy to grow Came in many varieties Easily manipulated Can self Fertilize Readily available
Importance of G. Mendel studying peas?
Deduced fundamentals of genetics
Monohybrid Cross definition
A cross between purebred parent plants that differ in only one character/trait
What are Hybrids?
The offspring of two different purebred varieties
Parental plants are the ___ generation
P
Parents hybrid offsprings are the ____ offsprings
F1
Across of the F1 plants form the ____ generation
F2
Phenotype definition
An organism’s physical appearance
Genotype definition
An organisms genetic makeup
Mendel developed how many hypotheses from the monohybrid cross
4 Hypotheses
Mendel Hypotheses from Monohybrid Cross (1)
The alternative version of genes are called alleles
Mendel Hypotheses from Monohybrid Cross (2)
For each inherited character, organism inherits two alleles, one from each parent. Can be Homozygous or Heterozygous
Homozygous definition
An organism is homozygous for that gene if both alleles are identical
Heterozygous Definition
AN organism is heterozygous for that gene if the alleles are different
Mendel Hypotheses from Monohybrid Cross (3)
If two alleles of inherited pair differ,
- ) one determines organism’s appearance and is called dominant allele
- ) Not relevant, is called recessive allele.
Mendel Hypotheses from Monohybrid Cross (4)
Each organism contains two alleles for each trait and the alleles segregate (separate_ during the formation of gametes. This is called the Law of Segregation
Gene Locus definition
A specific location of a gene along a chromosome
Can they have multiple alleles of a gene at the same locus?
Yes, Homologous chromosomes have alleles of a gene at the same locus
What does a genotype of PP get you?
Homozygous for the dominant allele
What does a genotype of aa get you?
Homozygous for the recessive allele
What does a geotype of Bb get you?
Heterozygous, with one dominant and one recessive allele
Rules of Probability
Apply to the inheritance of single gene traits. If genotypes of parents, it is possible to establish a childs chances for inheriting a particular genotype and thus for having a particular trait
Punnet Square Highligts
Four possible combination of gametes and the four possible offspring are in the F2 generation
In a normal Punnet Square, how many PP would you get?
One
In a normal Punnet Square, how many Pp would you get?
Two
In a normal Punnet Square, how many pp would you get?
One
Dihybrid Cross
The mating of parental varieties differing in two characters
What would result from a dihybrid cross?
Dependent Assortment
Independent Assortment
Law of Segregation
During gamete formation, the alleles of each gene segregate from each other so that each gamete caries only one allele for each gene
Law of Independent Assortment
Genes for different traits can segregate independently of the other genes during the formation of gametes
Testcross
Is a mating between an individual of dominant phenotype (but unknown genotype (Bb or BB?) and a homozygous recessive individual.
Example of Family Pedigree, Mendel’s Principles on the inheritance of many human traits
Earlobe Attachment Toungue Rolling Dimples Handednes Freckles Curly-Straight Hair
Dominant TRaits are not necessarily
Normal or More Common
Wild-Type traits are
typical form as it occurs most often in nature and not necessarily specified by dominant alleles
How can inbreeding occur?
Prolonged geographic isoloation of certain populations can lead to this, through the mating of close relatives
Why can inbreeding by harmful?
Inbreeding increases the chance of offspring that are homozygous for a harmful recessive trait
Many human traits show..
simple inheritance patterns and are controlled by a single gene of autosomes
Most human genetic disorders are ____
Recessive
How can someone be a carrier of a disorder
Individuals who have the recessive allele but appear normal are carriers of the disorder
Lethel Recesive; what if you have aa?
You are affected
Lethel Recesive; what if you have Aa?
You are a carrier
Lethel Recesive; what if you have AA?
You are normal
What falls under Lethal Recessive
PKU
Sickle Cell Anemia
Tay Sachs
Cystic Fibrosis
Lethal Dominant; what if you have aa?
You are normal
Lethal Dominant; what if you have Aa?
You are affected
Lethal Dominant; what if you have AA?
You are affected
What falls under Lethal Dominant
Huntingtons Disease
Neurofibromatosis
Brachy/Polydactyly
Marfan’s Syndrome
(R) Albinism
Lack of pigment in skin, hair, and eyes
(R) Cystic Fibrosis
Excess mucus in lungs, digestive tract, liber; increased suspectibility to infections, death in early childhood
(R) Phenyketonuria (PKU)
Accumation of phenylalanine in blood; lack of normal skin pigment, Mental Retardation unless trated
Diseases more common among certain ethnic groups
There is no referenence to discrimination, can run in certain groups
(R) Sickle-Cell Disease
Sickled red blood cells; damage to many tissues
(R) Tay Sachs Disease
Lipid accumulation in brain cells; mental deficiency; blindness; death in childhood
(D) Achondroplasia
Dwarfism
(D) Alzheimers Disease
Mental Deterioration; Usually strikes late in life
(D) Hungintons Disease
Mental Deterioration and uncontrollable movements; strikes in middle age
(D) Hypercholesterolemia
Excess Cholesterol in blood; heart disease
PKU Symptoms ; Deficiency on Phe Hydroxylase
An enzyme needed to conver essential amino acid phe to tyr
PKU Symptoms; Phenylacetate Accumulation
Progessive intellectual disabilities or mental retardation until puberty
PKU Symptoms
Seizures Tremors or Jerky Hand/Leg Hyperactivity, stunted growth Eczema Distinct odor in breath, skin, or urine. Orange urine Lighter Skin
High Phenylanine Foods
Fish Beans Dairy Diet Soda What Eggs Nuts & Legumes Meat
Low Phenylanine Foods
Most Vegetables Sugars Low-Protein Most Fruit Special Breaks/Cookies/Crackers
Cystic Fibrosis
Most common lethal genetic disease USA.
Caused by a recessive allele carried by about 1/31 Americans.
How does Cystic Fibrosis work
Impaired transport of CL- ions in lungs
Asthma
Salty Skin, “big” appetite
Large Greasy stools
Achondroplasia
Is a form of dwarfism
Achondroplasia works how?
Homozygous dominant genotype causes death of the embryo. Thus the only heterozygotes have this disorder
Huntingtons disease
Leads to the degeneration of the nervous system, does not usually begin until middle age.
Huntingtons Disease details
Causes involuntary movements
Causes degeneration in many regions of the brain and spinal cord
What faulty gene causes Huntingtons Disease
Cause by a fauly gene for a protein called Huntingtin
What are the chances of getting Huntingtons if your parents has it?
You have a 50% chance of inheriting it
Huntingtons Disease appear when?
Symptoms manifested at a middle age = family planning problems
Marfan Syndrome - Autosomal Dominant
Range of Symptoms Disorder of human CT DEfects of Heart Valves Affect lungs, eyes, skeleton Tall, long limbs, thin fingers Scoliosis Flat Feet Crowded teeth
Polydactyly - Autosomal Dominant
Having extra fingers growing on a hand
Brachydactyly - Autosomal Dominant
Shortening of fingers & toes
Neurofibromatosis
Tumor Disorder; Tumors along the nervous sytem. Scoliosis, learning disabilities, vision disorder, epilepsy
Proteus Syndrome
(Elephant Man) ; Mutation in Neurobibromin (Involved in RAS pathway)
Progeria - Autosomal Dominant
Accelerated Aging
Amniocentesis ; Genetic Test Performed During Pregnancy
Collects cells from amniotic fluid
Chorionic Villus Sampling; Pregnancy Test Performed During Pregnancy
Removes cell from placental tissue
What happens in Incomplete Dominance?
F1 hybrids have an appearance between the phenotype of the two parents
What happens in Hypercholesterolemia? (Codominant)
Heterozygotes have blood cholesterol levels about twice as normal. About five times the normal amount of blood cholesterol. Heart attacks as early as 2
ABO Blood Groups
Humans blood groups have three alleles. IA, IB, & i
ABO Blood Groups info
More than 2 alleles of a gene are present in the population
An individual can have only two of the many alleles for each trait
Polygenic Inheritance
The additive effects of two or more genes on a single phenotype
Role of Environment and Genetics
Human characters a result from a combination of heredity and environment. Only genetic influences are inherited.
Linked Genes
Are located close together on a chromosome and tend to be inherited together
Thomas Hunt Morgan
Used the fruit fly Drosophila Melaogaster
Determined that some genes were linked based on the inheritance patterns of their traits
Sex Chromosomes for male?
XY
Sex chromosomes for females?
XX
Sex-Linked Gene
Any gene that is located on a sex chromosome
Where are most sex-linked genes found?
On the X Chromosome
Sex linked genes exhibit ______
unusual patterns of inheritance.
Examples include color blindness, hemophilia, Duchenne Muscular Dystrophy
Red-Green Colorblindness
A common human sex-linked disorder and caused by a malfunction of light-sensitive cells in the eyes
Sex linked traits are expressed more frequently in which gender?
Males, due to the fact that genes are located exclusively on the X chromosome
A female will be color blind if she recives the recessive color blind gene ____
blind gene on both Xs
A male will be color blind if he receives the recessive color blind gene on ____
one X Chromosome
Hemophilia
Is a sex-linked resessive blood-clotting trait that may result in excessive bleeding and perhaps death after minor cuts.
How many different factors come into affect with clotting?
13
Autosomal Trait
Is expressed differently in males and females
Male Pattern Baldness
Trait influenced by Dihydroxy TEstosterone and Androgen Receptor Gene on X.
