Unit 2: Mendelian and Genetics Flashcards
triage18
branch of biology that deals with heredity and variation of organisms
genetics
carry the hereditary information (genes)
chromosomes
________ -> DNA -> RNA -> proteins
genes
arrangement of nucleotides in DNA
chromosomes
contain DNA that codes for the same genes
homologous chromosomes
homologous regions code for the same _________
gene
both chromosomes have all the same genes in the same locations but different versions of those genes
homologous chromosomes
a unit of heredity
gene
exact replicas of genes
sister chromatids
two genes that occupy the same position on homologous chromosomes and that cover the same trait
alleles
a section of DNA sequence encoding a single protein
gene
the entire set of genes in an organism
genome
a fixed location on a strand of DNA where a gene or one of its alleles is located
locus
‘flavors’ of a trait
alleles
the physical appearance of an organism
phenotype
the genetic makeup of an organism
genotype
genotype + environment
phenotype
having two different genes for a particular characteristic
heterozygous
having identical genes (one from each parent) for a particular characteristic
homozygous
trait in which a gene is carried on a sex chromosome
sex-linked
the trait appears in the heterozygous condition
dominant
a genetic cross between two different genes that differ in two observed traits
dihybrid cross
trait controlled by genes on one of 22 pairs of autosomes
autosomal
the allele of a gene that masks or suppresses the expression of an alternate allele
dominant
does not appear in the heterozygous condition, only in homozygous
recessive
an allele that is masked by a dominant allele
recessive
first filial generation of a genetic cross
F1
a genetic cross involving a single pair of genes (one trait)
monohybrid corss
THEORY: traits of two parents “blend” together and inherited by the offspring
Blending Theory of Inheritance
a genetic cross where parents differ by a single trait
monohybrid cross
How many traits or characteristics did Mendel observe in pea plants?
7
parental generation
P
second filial generation of a genetic cross
F2
plant in Mendel’s experiment
pea plants
Enumerate the 7 traits or characteristics of pea plants observed in Mendel’s Experiment
round / wrinkled
yellow / green
purple / white petals
axial / terminal flowers
yellow / green unripe pods
inflated / pinched ripe pods
long / short stems
aka Mendel’s theory
Particulate Theory of Inheritance
aka the gene idea
Particulate Theory of Inheritance
THEORY: inheritance involves the passing of discrete units of inheritance, or genes, from parents to offspring
Particulate Theory of Inheritance
Who proved the Chromosome Theory of Inheritance?
Thomas Morgan
Who proposed the Chromosome Theory of Inheritance?
Walter Sutton
What was the subject used in proving the Chromosome Theory of Inheritance?
fruit fly
Enumerate the 3 patterns of inheritance
Principle of Dominance
Principle of Segregation
Principle of Independent Assortment
THEORY: genes are present within chromosomes inside the cell
Chromosome Theory of Inheritance
POI: one allele masked another, one allele was dominants over the other in the F1 generation
Principle of Dominance
THEORY: genes and chromosomes are in pairs in diploid cells
Chromosome Theory of Inheritance
POI: When gametes are formed, the pairs of hereditary factors (genes) become separated, so that each sex cell (egg/sperm) receives only one kind of gene
Principle of Segregation
POI: 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
a lethal genetic disease affecting Caucasians
Cystic Fibrosis
used to determine the probability of outcome of offspring
punnett square
looks like a windowpane
punnett square
Cystic Fibrosis is caused by mutant ___________ gene carried by 1 in 20 people of European descent
recessive
1 in _____ children will have
Cystic Fibrosis from 2 parent carriers
4
Cystic Fibrosis affects _________ in tissues
transport
Enumerate the steps in making a punnett square
- determine the genotypes of the parent organisms
- write down your “cross” (mating)
- draw a Punnett square
- put in the genotype of one
parent across the top and that
of the other parent down the left
side - fill in the boxes by copying
the row and column head letters
across or down into the empty
squares
1 in ______ Caucasian couples will be both carriers of
Cystic Fibrosis
400
Huntington Disease is also known as _________ because every child of a parent with HD has a 50/50 chance of inheriting the faulty gene
quintessential family disease
In Cystic Fibrosis, ___________ is accumulated in lungs, causing infections
mucus
a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain
Huntington Disease
The allele for
Huntington Disease is _________
dominant
mating that involve parents that differ in two genes (two independent traits)
dihybrid cross
If F1 generation is allowed to self-pollinate, Mendel observed ________(#) phenotypes
4
Test cross with a _____________ individual
homozygous recessive
performed when you have an individual with an unknown genotype
test cross
type of relationship between alleles, with a heterozygote phenotype intermediate between the two homozygote phenotypes
Incomplete Dominance
When F1 generation is self-pollinated, the F2 generation ratio is __________
1:2:1
colorblindness is an example of a ___________ trait
sex-linked
colorblindness gene is carried only by _____ sex chromosome
x
In colorblindness, the Y chromosome is _________ than the X chromosome and contains only limited genes
shorter
autosomal traits that are influenced by sex
sex-influenced
Sex-influenced traits: if a male has one __________ allele, he will show that trait, but it will take _________ recessive for the female to show that same trait
recessive
2
both alleles are simultaneously expressed in the heterozygote
codominant traits
genes that are likely to be inherited together because they are physically close to one another on the same chromosome
linked genes
an example of codominant traits is __________
blood type
a section of DNA sequence encoding a single protein
Gene
the entire set of genes in an organism
genome
two genes that occupy the same position on homologous chromosomes and that cover the same trait
Alleles
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
genetic makeup of an organisms
genotype
physical appearance of an organism
Phenotype
Genotype + Environment
Phenotype
Having identical genes (one from each parent) for a particular characteristic
Homozygous
having two different genes for a particular characteristic
Heterozygous
a Trait in which a gene is carried on a sex 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 all
dominant
the trait appears in the heterozygous condition
DOminant
An allele that is masked by a dominant allele
Recessive
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
a genetic cross between two different genes that differ in two observed traits
Dihybrid Cross
What does this mean? (P)
Parental generation
What does this mean? (F1)
First filial generation; offspring from a genetic cross
What does this mean ? (F2)
Second filial generation of a genetic cross
It is when you follow strictly the Punnett Square
Single gene disease – Mendelian gene/trait
most common expression of a particular allele combination in a population. It may be recessive or dominant
ex. Black hair for all Asian (Filipinos)
Wild type phenotype
Variant of a (wild type) gene’s expression that arises when the gene undergoes a change, or mutation
Nahaluan ung Wild type Pheno,
ex. Blonde Asian/FIlipino
Mutant Phenotype
An illness that typically begins in early adulthood, causing
uncontrollable movements and changes in behavior and thinking (cognition), with death 15 to 20 years later
Huntington disease
How many percent of people who have HD are under age 20.
10%
Characteristics of Single-Gene Diseases
In families, we can deduce the probability that a particular person has inherited a single-gene disease by considering how he or she is related to an affected relative.
By using what?
Punnett Square
T/F: Genes do not like or dislike certain types of people; rather, mutations stay in certain populations because we tend to have children with people similar to ourselves.
True
2 example of single-gene diseases
Sickle cell disease
Muscular dystrophy
Many single- gene diseases affect fewer than ___ in 10,000 individuals.
1
This consist 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 “de novo”
Tests of trio
What do you call ung wala sa genetics nila pero nagkaroon sya like sya ung nauna?
de novo
Traits of two parents “blend” together and inherited by the offspring
Blending Theory of Inheritance
Particulate Theory of Inheritanceis aka the _____________
Gene Idea
Chromosome Theory of Inheritance is Proposed by ________ and
proved by ___________ using _________.
Proposed by Walter Sutton
Proved by Thomas Morgan
using fruit fly
Chromosome Theory of Inheritance
Genes and chromosomes are in
pairs in (diploid/haploid) cells
Diploid cells
What pattern of Inheritance?
One allele masks another, one allele was
dominant over the other in the F1
generation.
Principle of Dominance
What type of Patterns of Inheritance?
When gametes are formed, the pairs of
hereditary factors (genes) become separated,
so that each sex cell (egg/sperm) receives only
one kind of gene.
Principle of Segregation
What type of Patterns of Inheritance?
Genes located on different chromosomes will
be inherited independently of each other.
Principle of
independent assortment
Mendel noted that short plants crossed to other short plants were
“true-breeding,”
What does it mean?
always producing the same phenotype, in this case
short plants.
Huntington’s Disease
Some dominantly inherited diseases are said to be due to a (“lose/gain-of-function,”) because they result from the action of an
abnormal protein that interferes with the function of the normal protein.
extra protein they produce interfering in their nerves
Huntington disease results from a (lose/gain-of-function) in which the dominant mutant allele encodes an abnormally long protein that prevents the normal protein from functioning in certain brain cells.
“gain-of-function”
Homozygous/Hetereozygous
They can supply half the recessive allele. They will have mid-way amount of enzymes
Heterozygous
An individual with two different recessive alleles for the same gene is termed what?
Some people who have inherited diseases
compound heterozygote.
Child has a recessive allele from each parent with the variant located at a different position within the same gene
Compound Geterozygous (CH) Variants
How is nucleotide inheritance determines?
In terms of Laboratory-based?
10x Genomics or fosmid pool-based startegy
How is nucleotide inheritance determines?
In terms of Computer-based?
SHAPEIT2,Beagle, Eagle2,HapCUT2
Why study CH variants?
CH variants are understudied in ___________ disease
Pediatric disease
Why study CH variants?
May contribute to ________onset
Early disease onset
was the first genetic disorder for which mass post-natal genetic screening was available, beginning in the early 1960s, atypical cases were detected almost immediately.
a. Phenylketonuria
b. Tay–Sachs disease
c. Sickle cell syndromes
Phenylketonuria
Molecular analysis of the genome was not yet possible, but protein sequencing revealed
cases caused by compound heterozygosity
a. Phenylketonuria
b. Tay–Sachs disease
c. Sickle cell syndromes
a. Phenylketonuria
disease may present in juvenile or
adult onset forms, often as the result of compound heterozygosity between two alleles, one that causes the classic infantile disease in homozygotes and another that allows some residual HEXA enzyme activity.
a. Phenylketonuria
b. Tay–Sachs disease
c. Sickle cell syndromes
Tay–Sachs disease
A variety of sickle cell disorders result from inheritance of the sickle cell gene in
a compound heterozygous manner with other mutant beta globin genes
a. Phenylketonuria
b. Tay–Sachs disease
c. Sickle cell syndromes
Sickle cell syndromes
. These disorders include sickle
cell-beta thalassemia. In the case of sickle cell anemia, an individual with one allele for hemoglobin S and one allele for hemoglobin C would still develop the disease, despite being heterozygous for both genes.
a. Phenylketonuria
b. Tay–Sachs disease
c. Sickle cell syndromes
c. Sickle cell syndromes
A recessive trait is said to arise from a “loss/gain-of-function” because the recessive allele usually prevents the production or activity of the normal
protein
“loss-of-function”
On the RECESSIVENESS principle
The one normal allele, therefore, compensates for the mutant one, to which it is
dominant/recessive.
dominant
On the RECESSIVENESS principle
T/F: The basis of an inborn error of metabolism is easy to picture. These
diseases are typically recessive because the half normal amount of the
enzyme that a carrier produces is usually sufficient to maintain health. The
one normal allele, therefore, compensates for the mutant one, to which it is
dominant.
TRUE
On the RECESSIVENESS principle
Recessive diseases tend to be more severe, and produce symptoms earlier,
than dominant diseases. Disease-causing recessive alleles remain in populations because healthy heterozygotes pass them to future generations.
True
On the RECESSIVENESS principle
Most autosomal recessive conditions appear unexpectedly in families, because they
are transmitted silently, through (homozygotes/heterozygotes) (carriers)
heterozygotes
On the RECESSIVENESS principle
Marriage between relatives introduces ________, which means “shared blood”—a figurative description, because genes are not passed in blood.
consanguinity
On the RECESSIVENESS principle
Alleles inherited from shared ancestors are said to be “________________________”
identical by descent.
Comparison of Autosomal Dominant and Autosomal Recessive Inheritance
Males and females affected, with equal frequency.
a. Autosomal Dominant
b. Autosomal Recessive
c. Both
Both
Comparison of Autosomal Dominant and Autosomal Recessive Inheritance
Successive generations affected until no one inherits the mutation
a. Autosomal Dominant
b. Autosomal Recessive
c. Both
A.
Comparison of Autosomal Dominant and Autosomal Recessive Inheritance
Affected individual has an affected parent, unless he or she has a de novo mutation
a. Autosomal Dominant
b. Autosomal Recessive
c. Both
A.
Comparison of Autosomal Dominant and Autosomal Recessive Inheritance
Can skip generations
a. Autosomal Dominant
b. Autosomal Recessive
c. Both
B.
Comparison of Autosomal Dominant and Autosomal Recessive Inheritance
Affected individual has parents who are affected or are carriers (heterozygotes)
a. Autosomal Dominant
b. Autosomal Recessive
c. Both
B.
Mendel’s 1st law
reflects d actions of chromosomes nd d
genes they carry during meiosis.
(An individual with two identical alleles for
a gene is homozygous for that gene. An individual with two different alleles is heterozygous—what Mendel called “non-true-breeding” or “hybrid.”)
Law of Segregation
Mendel’s 1st Law
Gametes combine at random. A t-bearing oocyte is neither more nor less attractive to a sperm than is a T-bearing oocyte. These two factors—equal allele distribution into gametes and random combinations of gametes— underlie Mendel’s Law of _______
Segregation
Mendel’s 2nd Law is what?
Law of independent assortment
Mendel’s 2nd Law
states that for two genes on different
chromosomes, the inheritance of one gene does not influence the chance of inheriting
the other gene
The two genes are said to “independently assort” because they are packaged into gametes at random.
Law of Independent assortment
Two genes that are far apart on the same chromosome (see discussion on linkage) also appear to independently assort, because so many crossovers take place between
them that it is as if they are part of separate chromosomes
What is Principle 1?
a. Test cross/ Pedigree analysis
b. Punett square - Single test cross/monohybdrid
c. Dihybrid Cross
a
Law 1
a. Test cross/ Pedigree analysis
b. Punett square - Single test cross/monohybdrid
c. Dihybrid Cross
B.
Law 2
a. Test cross/ Pedigree analysis
b. Punett square - Single test cross/monohybdrid
c. Dihybrid Cross
C
■ A useful tool to do genetic crosses
■ Looks like a windowpane
■ Used to determine the probability of outcome of offspring
Punnett Square
a lethal genetic disease affecting
Caucasians.
1 in 400 Caucasian couples will be both
carriers of CF, 1 in 4 children
Caused by mutant recessive gene carried by 1 in
20 people of European descent.
affects transport in tissues – mucus is accumulated in lungs, causing infections.
Cystic Fibrosis(CF)
a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain
allele for Huntington’s disease is dominant
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)
Mating that involve parents that differ in two
genes (two independent traits)
For example, flower color:
P = purple (dominant)
p = white (recessive)
and stem length:
T = tall t = short
Case: Huntington Disease (HD) Dihybrid Cross
When you have an individual with an unknown
genotype, you do a ______.
Cross with a homozygous recessive individual.
For example, a plant with purple flowers can
either be PP or Pp… therefore, you cross the
plant with a pp (white flowers, homozygous
recessive)
Test cross
