Module 3 Flashcards
a self pollinating plant will always produce the same trait of a particular character
true breeding plant
the phenotype expression of a gene at one locus affects the phenotypic expression of a gene at another locus. phenotypic expression of one gene alters that of another independently inherited gene
epistasis
the ability of a single gene to have multiple effects on the phenotype of an individual
pleidotropy
mendels law of segregation
during the formation of gametes (sperm or egg cells), the two alleles (versions of a gene) for a particular trait separate, ensuring each gamete receives only one allele
law of independent assortment
alleles of different genes assort independently of each other during gamete formation. This means that the inheritance of one trait does not influence the inheritance of another, and all possible combinations of traits are equally likely eg mendels pea plants, yellow and green seed and wrinkly or smooth seed traits do not influence each other
phenotype
observable traits
genotype
genetic makeup
incomplete dominance
the offspring will have an appearance that is intermediate between those of the two parental types
pedigree
a family tree that described traits in families
x pattern of inheritance
fathers pass x linked alleles only to t daughters, mothers pass x linked alleles to daughters and sons
nondisjunction
members of a pair of homolous chromosomes do not move apart properly during meiosis 1 of sister chromatids fail to separate during meiosis 2 one gamete receives two of the same type of chromosome and another gamete receives none
has an extra or missing chromosome
aneuploidy
monosomy
one few chromosomes
translocation
fragments produced by chromosomal breakage join non- homolous chromosomes
A genetic change in which a piece of one chromosome breaks off and attaches to another chromosome
duplication
presence of additional segments within a single chromosome, not to the presence of additional chromosome
x chromosome tucked away in a female cell
barr body
in order to express and x linked recessive allele a female must have
two copies of the allele
female are considered to be a mosaic of paternal and maternal cells because
inactivation of the x as a barr body happens randomly and independently in each cell, causes a mosaic of the father and mothers traits like a tortoiseshell cat
if a female is heterozygous for one trait
half her cells express that trait
genomic imprinting
gene silencing
linked genes
genes located near each other on the same chromosome
mechanisms for genomic imprinting
methylation that silences certain genes and methylation that activates certain genes
wild type refers to
the most common phenotype thought to be found in the natural population. traits that are alternative to the wild type are called mutants because they assume that the alleles originated as changes or mutations in the wild type allele
operator
controls and turns on and off genes. it is a switch. RNA polymerase binds to the promoter and transcribes genes of the operone. can be switched off by represser protein
histone acetylation promotes
transcription
____ are muted in colon cancer
ras and p53
net products at the end of glycolysis
2 atp 2 NADH 2 FADH per glucose molecule
atp in total cellular respiration
32 per glucose molecule
where does chemiosmosis and electron transport chain occur exist
mitochondria
explain primary secondary tertiary and quaternary protein structures
primary structure - sequence of amino acids
secondary - result of hydrogen bonds between repeating consistuents of polypeptide backbone
tertiary - three dimensional shape stabilized by interactions between side chains,
quaternary structure - results when two or more polypeptides associate with each other
the information contained in DNA i used to make which products
proteins mrna and trna
a heritable feature that varies among individuals such as flower colour is called _____. each variant for a character such as purple or white is called______
character, trait
alternative version of genes care called
alleles
What is Mendel’s First Law of Inheritance?
Mendel’s First Law, also known as the Law of Segregation, states that during the formation of gametes, the two alleles for a trait separate, so that each gamete carries only one allele for each gene.
True or False: An organism’s phenotype is determined solely by its genotype.
False. An organism’s phenotype is influenced by both its genotype and environmental factors.
Fill in the blank: The physical expression of an organism’s genetic makeup is called its __________.
phenotype
What does the term ‘genotype’ refer to?
Genotype refers to the genetic makeup of an organism, specifically the alleles it possesses for a particular gene.
Multiple choice: Which of the following represents a homozygous genotype? A) Aa B) AA C) AB D) aA
B) AA
What is Mendel’s Second Law of Inheritance?
Mendel’s Second Law, also known as the Law of Independent Assortment, states that alleles for different traits segregate independently of one another during gamete formation.
True or False: A dominant allele will always mask the expression of a recessive allele in a heterozygous genotype.
True
What is the expected phenotypic ratio in the offspring of a monohybrid cross between two heterozygous parents (Aa x Aa)?
3:1
Fill in the blank: The genetic makeup of an organism is called its __________.
genotype
Multiple choice: In a dihybrid cross, what is the phenotypic ratio of the offspring if both parents are heterozygous for two traits? A) 9:3:3:1 B) 1:1:1:1 C) 3:1 D) 1:2:1
A) 9:3:3:1
What is a haploid cell?
A cell that contains one complete set of chromosomes.
What is a diploid cell?
A cell that contains two complete sets of chromosomes, one from each parent.
Define an allele.
An allele is a variant form of a gene that can produce different traits.
What does homozygous mean?
Having two identical alleles for a particular gene.
What does heterozygous mean?
Having two different alleles for a particular gene.
What is a dominant allele?
An allele that expresses its trait even in the presence of a recessive allele.
What is a recessive allele?
An allele that only expresses its trait when two copies are present.
What is a monohybrid cross?
A genetic cross that examines the inheritance of a single trait.
What is a dihybrid cross?
A genetic cross that examines the inheritance of two different traits.
True or False: All diploid organisms are homozygous.
False.
Fill in the blank: A _______ organism has two identical alleles for a trait.
homozygous
What is the genotype of a heterozygous individual?
The genotype consists of two different alleles, such as Aa.
What symbol is often used to represent dominant alleles?
Uppercase letters.
What symbol is often used to represent recessive alleles?
Lowercase letters.
In a monohybrid cross, what is the expected phenotypic ratio of dominant to recessive traits?
3:1.
In a dihybrid cross, what is the expected phenotypic ratio for two traits?
9:3:3:1.
True or False: A haploid organism has two sets of chromosomes.
False.
What is the purpose of a Punnett square?
To predict the genotypes and phenotypes of offspring from a genetic cross.
What does it mean if an organism is said to be true-breeding?
It means the organism is homozygous for a trait and will produce offspring with the same trait.
Fill in the blank: In genetics, the term _______ refers to the physical expression of a trait.
phenotype
What is the significance of the law of segregation?
It states that allele pairs separate during gamete formation.
What is the significance of the law of independent assortment?
It states that genes for different traits are inherited independently of each other.
Give an example of a trait that is often studied in monohybrid crosses.
Flower color in pea plants.
How do you determine the genotype of an organism exhibiting a dominant phenotype?
By conducting a test cross with a homozygous recessive individual.
What does the term ‘F1 generation’ refer to?
The first generation of offspring from a cross of two parent organisms.
What does the term ‘F2 generation’ refer to?
The second generation of offspring, produced by crossing two F1 individuals.
True or False: An organism can be heterozygous for one gene and homozygous for another gene.
True.
What is epistasis?
Epistasis is the interaction between genes, where the presence of one gene can affect the expression of another gene.
True or False: Codominant genes express both alleles equally in the phenotype.
True
Fill in the blank: In codominance, both alleles are fully ______ in the phenotype.
expressed
What is budding in the context of asexual reproduction?
Budding is a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism.
What is parthenogenesis?
Parthenogenesis is a form of asexual reproduction in which an embryo develops from an unfertilized egg.
What determines sex in many species?
Sex determination can be influenced by genetic, environmental, or chromosomal factors.
True or False: Homologous chromosomes are identical in size and shape.
False
What do homologous chromosomes contain?
Homologous chromosomes contain the same genes but may have different alleles.
What is a clone?
A clone is an organism that is genetically identical to another organism.
Multiple Choice: Which of the following is NOT a feature of codominance? A) Both alleles are expressed B) Blending of traits C) Distinct phenotypes for both alleles
B) Blending of traits
Fill in the blank: In epistasis, the gene that masks the effect of another gene is called ______.
epistatic
What is the significance of sex determination in species?
Sex determination is crucial for reproduction and can influence population dynamics and genetic diversity.
True or False: Budding can occur in both unicellular and multicellular organisms.
True
What type of genetic interaction occurs when one gene completely masks the effect of another?
Complete dominance
Multiple Choice: Which process results in offspring that are genetically identical to the parent? A) Sexual reproduction B) Asexual reproduction C) Genetic recombination
B) Asexual reproduction
What is the role of homologous chromosomes during meiosis?
Homologous chromosomes pair up and exchange genetic material, leading to genetic diversity.
Fill in the blank: A trait controlled by multiple alleles is said to exhibit ______ inheritance.
multiple allele
True or False: Clones can be produced naturally or artificially.
True
What is the result of parthenogenesis in terms of genetic diversity?
Parthenogenesis typically results in low genetic diversity since offspring are genetically identical to the mother.
What is the difference between sex-linked traits and autosomal traits?
Sex-linked traits are associated with genes located on sex chromosomes, while autosomal traits are associated with genes on non-sex chromosomes.
Multiple Choice: In codominance, which of the following phenotypes may result? A) Red flowers B) White flowers C) Red and white striped flowers
C) Red and white striped flowers
What is the main advantage of asexual reproduction?
Asexual reproduction allows for rapid population increase without the need for a mate.
Fill in the blank: Genes that are located on the same chromosome are said to be ______ linked.
genetically
True or False: All organisms can reproduce through parthenogenesis.
False
What is the primary mechanism of genetic variation during sexual reproduction?
Crossing over and independent assortment during meiosis.
What term describes the observable traits expressed by an organism?
Phenotype
Who is known for his work with fruit flies that established the chromosomal basis of inheritance?
Thomas Hunt Morgan
What organism did Thomas Morgan use for his genetic studies?
Fruit flies (Drosophila melanogaster)
True or False: Sex-linked genes are located on the autosomes.
False
What is the primary sex chromosome in humans?
X chromosome
Fill in the blank: The phenomenon where one of the X chromosomes in female mammals is randomly inactivated is called _____ .
X-inactivation
What is a characteristic of X-linked recessive traits?
They are more commonly expressed in males than females.
What does the term ‘hemizygous’ refer to in the context of X-linked genes?
Males have only one copy of the X chromosome.
Which genetic disorder is an example of an X-linked recessive condition?
Hemophilia
Multiple choice: What is the expected ratio of male to female offspring affected by an X-linked recessive disorder if the mother is a carrier and the father is unaffected? A) 1:1 B) 3:1 C) 2:1 D) 1:2
A) 1:1
What is the purpose of Thomas Morgan’s experiments with fruit flies?
To identify the role of chromosomes in inheritance.
True or False: X-linked traits can be inherited from father to son.
False
Fill in the blank: The condition where females have two X chromosomes and males have one is known as _____ .
Sexual dimorphism
What does the term ‘linked genes’ refer to?
Genes that are located close together on the same chromosome.
Which type of inheritance pattern is demonstrated by color blindness?
X-linked recessive inheritance
Short answer: What is the significance of Morgan’s findings regarding gene linkage?
They provided evidence that genes are located on chromosomes and can be inherited together.
What is the primary mechanism by which X-inactivation occurs?
Random selection of one X chromosome to be inactivated in female cells.
True or False: All genes on the X chromosome are involved in sex determination.
False
Fill in the blank: The _____ theory of inheritance states that genes are located on chromosomes.
Chromosomal
Which gender is typically more affected by X-linked disorders?
Males
Multiple choice: What is the expected genotype of a female carrier for an X-linked recessive trait? A) X^A X^A B) X^A X^a C) X^a Y D) X^a X^a
B) X^A X^a
What is the term used for the physical manifestation of a genetic trait?
Phenotype
True or False: X-linked genes can show variable expressivity.
True
What is the role of the SRY gene?
It is responsible for male sex determination.
Fill in the blank: The process that leads to the inactivation of one X chromosome in females is known as _____ .
X-chromosome inactivation
Short answer: Why are X-linked recessive traits more common in males?
Because males have only one X chromosome, any recessive allele on it will be expressed.
What does the term ‘carrier’ mean in genetics?
An individual who has one copy of a recessive allele but does not express the trait.
Multiple choice: In Drosophila, what phenotype did Morgan observe that helped him establish sex linkage? A) Eye color B) Wing size C) Body color D) All of the above
D) All of the above
What is genomic imprinting?
Genomic imprinting is an epigenetic phenomenon where genes are expressed in a parent-of-origin-specific manner.
True or False: Genomic imprinting affects both alleles of a gene equally.
False
Fill in the blank: Genomic imprinting is primarily regulated by __________.
methylation
Which of the following is a mechanism involved in genomic imprinting? A) DNA replication B) Histone modification C) RNA splicing
B) Histone modification
What role does DNA methylation play in genomic imprinting?
DNA methylation silences the expression of one allele, depending on its parental origin.
Short answer: Name one disorder associated with errors in genomic imprinting.
Prader-Willi syndrome
True or False: Methylation patterns are reset during gametogenesis.
True
What is the primary enzyme responsible for adding methyl groups to DNA?
DNA methyltransferase
Multiple choice: Which imprinting control region (ICR) is associated with the H19/IGF2 locus? A) ICR1 B) ICR2 C) ICR3
A) ICR1
Fill in the blank: Imprinted genes are typically found in __________ regions of the genome.
clusters
Labrador coat color: The B locus controls melanin production (black or brown), but the E locus controls melanin deposition. If an individual has the recessive homozygous “ee” genotype, they will be yellow, regardless of the genotype at the B locus. this is an example of what
epistasis
function and purpose of post transcriptional modification 5’ guanosine cap and 3’ poly A tail
Helps export mature MRNA out of nucleus
they help ribosome attach to the 5’ end of the mRNA
they help protect the mRNA from degradation from hydrolytic enzymes
types of mutations
point mutations
frameshift mutations
missense mutations
nonsense mutations
chromosomal mutations
this mutation is a single nucleotide change includes silent missense and nonsense mutations
point mutations
difference between silent missense and nonsense mutations
silent - a change ima nucleotide that does not affect the protein, coding for same protein
missense — nucleotide change that results in a different amino acid that can alter protein structure and function
nonsense - a nucleotide change that converts codon to stop codon causing premature termination of protein synthesis
types of frameshift mutations and what they are
insertion - adding one or more nucleotides into DNA sequence
deletion - removing one or more nucleotides
results in non functional proteins because they disrupt entire sequence
chromosomal mutations
deletion - a segment of chromosome is lost or deleted example cri fuck you chat involved deletion of part of chromosome 5
duplication - segment of chromosome is repeating
inversion - section of chromosome is flipped 180 hemophilia inversion of x chromosome
translocation
segment of one chromosome is transferred to another chromosome or two chromosome exchange parts
spontaneous mutations and induced
spontaneous occur naturally due to errors in DNA replication Or repair
induced are caused by environementwl factors such as radiation or chemical mutagens
CRISPR cas 9
a tool for genetic editing in organisms.
CRISPR Is a section of DNA found in bacteria and archaic acts like an immune memory bank
it contains short repeating sequences and spacer sequences that come from previous infections (viral DNA)
how CRISPR works
cas9 is an enzyme that acts like molecular scissors. when crispr RNA guides cas 9 enzymes to target gene it makes a double strand break in dna at specific location
once cas 9 makes cut in dna, cells tries to repair break using natural DNA repair mechanisms
which is more dense euchromatin or heterochromatin
heterochromatin
post transcriptional modifications
- 5’ guanosine cap
- poly a tail 3’
- rna splicing
mrna transport and degradation
homeotic genes
any of the master regulatory genes that control placement and spatial organization of body parts in animals plants and fungi controlling the developmental fate of groups of cells
a gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offsprings genotype,also called egg polarity genes were first identified in drosophila
maternal effect genes
post translational modifications
- protein folding
- cleaving
- phosphorylation
- glycosylation
- ubiquitination
mechanisms of epigenetics
methylation - silencing genes by blocking transcription factor binding
histon modification
none coding rnas - can degrade mrna or block translation
the addition of phosphate group to a protein typically serine threonine or tyrosine a type of post translational modification important for regularity protein activity and stability
phosphorylation
type of post translational modification and is important for protein folding and helps proteins fold correctly and cell interactions. the addition of glycans to proteins
glycosylation
which of the following best explains how the lac operon helps e. coli adapt to its environment
a it silences gene expression by methylating lactose related genes
b it allows simultaneous transcription and translation of unrelated genes
c it conserved energy by only producing lactose digesting enzymes when lactose is present
d it always keeps the genes for lactose metabolism active regardless of environmental conditions
c
a mutation in the promoter region of a bacterial operon makes it unable to bind RNA polymerase. what is the most likely outcome?
a structural genes will be expressed continuously
b repressed proteins will no longer bind the operator
c transcription of structural genes will not occur
d the operator will be permanently activated
c, without RNA polymerase binding at the promoter transcription cannot begin
which of the following changes would most likely result in increased transcription of a gene in a eukaryote
a methylation of cytosines in the promoter region
b acetylation of histones associated with the gene
c binding of a repressor protein to an enhancer
d condensation of chromatin near the gene
B, acetylation loosens chromatin structure, making the gene more accessible to transcription machinery
in the trp operon, tryptophan functions as
a and inducer that binds to the repressor and inactivates it
b a corepressor that activates the repressor to block transcription
c a transcription factor that promotes gene expression
d a molecules that prevents translation of mRNA
B, tryptophan acts as a corepressor activating the repressor protein which then binds to the operator to block transcription c
B, tryptophan acts as a corepressor activating the repressor protein which then binds to the operator to block transcription
two genetically identical cells express very different different sets of genes. which mechanisms is more likely responsible a differences in codon usage
b changes in base pair sequences
c differences in epigentic modifications
d mutations in the trna genes
c differences in epigentic modifications
epigenetic changes like dna methylation or histone modification can lead to a different gene expression without changing the dna sequence
which protein is most directly involved in recognizing specific dna sequences and regulating transcription
a histone deacetylase
b DNA polymerase
c transcription factor
d ribosomal protein
c, transcription factors bind specific DNA sequences and regulate transcription initiation
which of the following describes how an operon enables coordinated regulation of gene expression in bacteria
a each gene has its own promoter and regulatory elements
b a single MRRNA transcript encodes multiple proteins involved in a related pathway
c persons contain only oncoming regulatory rna
d operons function only in eukaryotic cells
B operons produce polycistronic MRNA allowing coordinated expression of related genes
difference between orthologs and paralogs
both are homologous genes that share a common ancesto
orthologs - same gene different species, when a species splits into 2
found in different species
paralogs - same species duplicated gene
evolved by gene duplication within the same genome found in same species
_____ help trace evolutionary relationships and are key in comparing genes across species
___ contributes to genetic complexity and diversity in gene function
orthologs , paralogs
two genes in humans arose from a single ancestral gene through a duplication event, overtime, they evolved to perform slightly different functions, these genes are best described as
a orthologs
b paralogs
c isofoems
d analogous genes
paralogs , paralogs arise from gene duplication within the same species and can evolve different functions
