Unit 2 Part 1: Mendelian Genetics Flashcards
Branch of biology that deals with heredity and variation of organisms.
Genetics
Carry the hereditary information (genes)
Chromosomes
Gene Expression Sequence
DNA → RNA → Proteins
Contain DNA that codes for the same genes
Homologous Chromosomes
Example of Homologous Chromosome
XY Chromosome
T/F: Sister chromatid may be identical but not necessarily same on the 23rd chromosome
T
a unit of heredity; a section of DNA sequence encoding a single protein
Gene
Composed of DNA and defines portion of a DNA
Gene
Combination of all genes
Genome
2 Type of Genomes
- Nuclear
- Mitochondrial
Two genes that occupy the same position on homologous chromosomes and that cover the same trait (like ‘flavors’ of a trait).
Alleles
A fixed location on a strand of DNA where a gene or one of its alleles is located.
Locus
T/F: Genome reflects the size and complexity of structure but not the intelligence
T
The genetic makeup of an organisms
Genotype
The physical appearance
of an organism (Genotype + environment)
Phenotype
Having identical genes (one from each parent) for a particular characteristic
Homozygous
Having two different genes for a particular characteristic
Heterozygous
T/F: Phenotype is controlled by genotype so genotype is representation of the genes
T
A trait in which a gene is carried on a sex chromosome (inherited from 23rd chromosome)
Sex-linked trait
Traits controlled by genes on one of 22 pairs of autosomes
Autosomal trait
The allele of a gene that masks or suppresses the expression of an alternate allele; the trait appears in the heterozygous condition
Dominant
An allele that is masked by a dominant allele; does not appear in the heterozygous condition, only in homozygous
Recessive
A genetic cross involving a single pair of genes (one trait); parents differ by a single trait
Monohybrid cross
a genetic cross between two different genes that differ in two observed traits
Dihybrid cross
Offspring from a genetic cross
F1 First filial generation
T/F: NonMendelian involves only single genes (single gene disorder)
F; Mendelian
Is the most common expression of a particular allele combination in a population. Allele may be recessive or dominant.
Wild Type Phenotype
A variant of a gene’s expression that arises when the gene undergoes a change, or mutation.
Mutant Phenotype
2 Types of Mutation
- Point Mutation - isa lang nagbago
- Frame Shift - nagbago reading sequence
more DNA sequence changes = more severe = _________
extensive shifts
T/F: All cells harbor the mutation, if the person has inherited it.
T
Consisting of sick children and their parents can reveal whether the child inherited two disease-causing mutations from carrier parents, or whether a dominant mutation arose anew, termed “_________.”
Tests of “trios” , de novo
Traits of two parents “blend” together and inherited by the offspring
Blending Theory of Inheritance
7 traits or characteristics of
pea plants:
- Shape of the peas
- Color of the peas
- Color of the flower
- Color of unripe pods
- Shape of ripe pods
- Axial or terminal flowers
- Size of stems
He debunked the blending theory of inheritance
Gregor Mendel
He self-pollinated the first-generation offspring of pea plants.
Gregor Mendel
Are ideal for probing heredity because they are easy to grow, develop quickly, and have many traits that take one of two easily distinguishable forms.
Peas
Inheritance involves the passing of discrete units of
inheritance, or genes, from parents to offspring
Particulate Theory of Inheritance / Gene Idea
Chromosome Theory of Inheritance was proposed by _____ and proved by ______ using _____
Walter Sutton, Thomas Morgan, fruit fly
Genes are present within chromosomes inside the cell
Chromosome Theory of Inheritance
Genes and chromosomes are in pairs in diploid cells
Chromosome Theory of Inheritance
Patterns of Inheritance
One allele masked another; one allele was dominant over the other in the F1 generation.
Principle of Dominance
Patterns of Inheritance
When gametes are formed, the pairs of hereditary
factors (genes) become separated through cellular
division wherein each gene does not affect the other
though undergoing processes, so that each sex cell
(egg/ sperm) receives only one kind of gene
Principle of Segregation
Patterns of Inheritance
Genes located on different chromosomes will be
inherited independently of each other
Principle of Independent Assortment
A useful tool to do genetic crosses
Punnett Square
Used to determine the probability of outcome of offspring
Punnett Square
Looks like a windowpane
Punnett Square
Parent Genotypes: Aa and aa; Cross Aa x aa
What is the Resulting Genotype?
50% heterozygous Aa, 50% homozygous aa
Pattern of Inheritance
Mendel noted that short plants crossed to other short plants were “true- breeding,” always producing the same phenotype, in this case short plants.
Principle of Dominance
Pattern of Inheritance
Some dominantly inherited diseases are said to be due to a “gain-of-function,” because they result from the action of an abnormal protein that interferes with the function of the normal protein.
Principle of Dominance
Pattern of Inheritance
Huntington Disease
Principle of Dominance
T/F: Dominant disease whose symptoms do not appear until adulthood, or that do not severely disrupt health, remain in a population because they do not prevent a person from having children and passing on the mutation
T
T/F: Most genes have more than two alleles and more than two variations of the associated trait.
T
An individual with two different recessive alleles for the same gene
compound heterozygote
Child has a recessive allele from each parent with the variant located at a different position within the same gene
CH Variant
How is nucleotide inheritance determined?
- Laboratory-based: 10X Genomics / Fosmid Pool-Based Strategy
- Computer-based: SHA PEIT2, Beagle, Eagle 2, HapCUT2
first genetic disorder for which mass post-natal genetic screening was available, beginning in the early 1960s, atypical cases were detected almost immediately
Phenylketonuria
Is said to arise from a “loss-of-function” because the recessive allele usually prevents the production or activity of the normal protein
Recessive Trait
Marriage between relatives introduces ________, which means “shared blood”—a figurative description, because genes are not passed in blood.
consanguinity
Alleles inherited from shared ancestors are said to be
“identical by descent”
Males and females affected with equal frequency
Autosomal Dominant & Recessive
Successive generations affected until no one inherits the mutation
Autosomal Dominant
Affected individual has an affected parent, unless he or she has a de novo mutation
Autosomal Dominant
Affected individual has parents who are affected or are carriers (heterozygotes)
Autosomal Recessive
Can skip generations
Autosomal Recessive
Reflects the actions of chromosomes and the genes they carry during meiosis. Because a gene is a long sequence of DNA, it can vary in many ways.
Law of Segregation
what Mendel called “non-true-breeding” or “hybrid”
Heterozygous
States that for two genes on different chromosomes, the inheritance of one gene does not influence the chance of inheriting the other gene.
Law of Independent Assortment
T/F: The two genes are said to “independently assort” because they are packaged into gametes at random.
T
T/F: Two genes that are far apart on the same chromosome also appear to dependently assort, because so many crossovers take place between them that it is as if they are part of separate chromosomes
F; independently assort
Principle 1 - Test cross/ Pedigree analysis
Law 1: ________
Law 2: ________
- Punett square - Single test cross/monohybdrid
- Dihybrid Cross
A lethal genetic disease affecting Caucasians.
Cystic Fibrosis
Caused by mutant recessive gene carried by 1 in 20 people of European descent
Cystic Fibrosis
Affects transport
in tissues – mucus is accumulated in lungs, causing infections
Cystic Fibrosis
If two parents carry the recessive gene of Cystic Fibrosis (c), that is, they are heterozygous (C, c), what is the probability of that their offspring will acquire cystic fibrosis
C C = normal
C c = carrier
c c = CF
50% Heterozygous Carrier
25% Homozygous Normal
25% Heterozygous CF
A fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain
Huntington Disease (HD)
known as the quintessential family disease because every child of a parent with HD has a 50/50 chance of inheriting the faulty gene
Huntington Disease (HD)
T/F: Allele for Huntington’s disease is dominant
T
What is the probability of the offspring acquiring the Huntington disease if one of the parents is heterozygous of the disease while the other is normal?
H = HD allele
hh = normal
Hh = heterozygous HD
50% Heterozygous Carrier
50% Homozygous HD
When you have an individual with an unknown genotype, you do a _________
Test Cross
Mating that involve parents that differ in two genes (two independent traits)
Dihybrid cross
Cross with a homozygous recessive individual
Test Cross
If you get all 100% purple flowers, then the unknown parent was?
PP
If you get 50% white, 50% purple flowers, then the unknown parent was
Pp
What chromosome carries that trait most of the time?
X chromosome because Y chromosome is short
