Genetics Final Exam Flashcards

Flashcards covering key vocabulary and concepts from the lecture notes.

Gene regulation

How a cell controls when and where something is produced and the primary mechanism is controlling gene transcription.

Example of gene regulation

The control of insulin production in response to blood sugar levels.

Transcription initiation

Selection of genes occurs and when the pre-initiation complex and RNA polymerase is collected.

Transcription Initiation in Eukaryotes

First the TBP (tata binding protein) binds to the tata binding consensus sequence in the promoter, and second, the pre-initiation complex assembles on the TBP in which contains the RNA polymerase holoenzyme

Transcription initiation in Prokaryotes (Bacteria)

Prokaryotes don't not have the TBP, instead they have the Sigma subunit that will bind to the promoter sequence. Then, the RNA polymerase holoenzyme will bind to the sigma Subunit

Sigma subunit

There are many different sigma factors and they recognize different promoter sequences

Prokaryotes (transcription initiation) characteristics

Functionally related genes that have the same promoter sequence are turned on at the same time. They have operons- Related genes that share the same promoter and No CRM

Eukaryotes (Transcription initiation) characteristics

Only one tata binding protein, TBP recognizes all promoter sequences, Each CRM may have binding sites for multiple transcription factors and CRM contains unique binding sites that enable differentiation transcription regulation

General transcription factors

Are components of pre-initiation complex and are universal for eukaryotic transcription

Specific transcription factors

Binds to specific sequences (enhancers) in the CRM and are NOT universal. (many are involved in activating transcription)

Consensus sequence

A sequence of DNA having similar structure and function in different organisms.

Changes in the chromatin structure affect gene expression in eukaryotes?

If the chromosome consist of Heterochromatin then the gene can not get the DNA because it is so condensed but if it consisted of Euchromatin the DNA can be accessed and expressed (accessibility to DNA).

Genetics

Heritable variation due to DNA sequence

Epigenetics

Heritable variation not due to DNA sequence (environmental Factors)

Histone acetylation

Adding acetyl groups to histone trails causing DNA positive charge to decrease allowing for the DNA-histones to loosen up (allowing DNA interaction access)

Histone deacetylation

Removal of acutely groups from the DNA-histones not allowing chromosomal access to the DNA

DNA methylation

Methyl groups get added to the DNA which in turn can block transcription completely near the transcription start site.

Methyl transfer

Enzymes use methyl groups on an old strand to methylate a new strand.

Functional non-coding RNAs

Long ncRNA, SnRNA, tRNa Micro RNA

Long ncRNA

Affect transcriptional intution

snRNA

Regulate Splicing

tRNa

Carries out translation

Micro RNAs

Blocks translation or targets degradation

non-coding RNA does Prokaryotes (Bacteria) use

Antisense RNAs

Antisense RNAs

Stops translation

Translation process in Prokaryotes

Ribosomes bind to the shine Dalgarno sequence to position itself over the start codon.

translation process for a Eukaryote

Ribosomes assemble and the 5’ UTR moves downstream and uses the Kozak sequence to find the start codon

What do tRNAs do in translation?

They decode the genetic code and provide a direct correspondence between codons and their corresponding amino acids.

Allosteric regulation

a process where the activity of a protein, often an enzyme, is modulated by the binding of a regulatory molecule (effector) at a site other than the active site

Allosteric inhibition

The active site does not allow for the substrate to fit

Allosteric activation

The substrate fits in its active site

Maternal effect

Maternal effect genes are genes expressed by the mother that influence the development of the offspring before the offspring's own genome is activated. These genes, expressed during oogenesis, produce RNA or proteins that are deposited in the egg, creating gradients that help establish the body's axes and control early embryonic development.

Post-Translational modifications

Assemble into multimers, Proteolytic Cleavage, phosphorylation, glycosylation, ubiquitination, methylation, acetylation, and lipid modification

Proteolysis

The breakdown of proteins or peptides into amino acids by the action of enzymes

Anterior to posterior development in Drosophila?

mRNAs are translated after fertilization into protein gradients, Bicoid and nanos generate gradients of hunchback and caudal, Gap genes subdivide embryo into regions, The pair-rule gene further divides into segments (expression is even skipped), Hox genes give the segments their identity

Bicoid deposited in the Drosophila

Deposited in the anterior (head)

Nanos deposited

Deposited into the posterior (rear)

Hunchback and caudal deposited

Uniformly (across the entire body)

Two expressions of gap genes

Kruppel (in the middle), Giant (two stripes around the middle)

Transcription factors for the gap genes

Bicoid, Nanos, Hunchback, Caudal

Gene networks

Known as gene regulatory networks, are computational models that represent how genes interact to regulate their expression and determine cell function. They depict the flow of information between genes, highlighting how one gene's activity influences the expression of another.

Oncogenes

They promote cell proliferation /survival (activating gene expression), If there is a mutation it can turn them constantly on, Usually are dominant mutations

Tumor-suppressor genes

Involves quality control functions (DNA repair, control of cell division), A Mutation make them permanently off (null mutation), Usually are recessive mutations

Processes when damage could result in hyperproliferation in cancer

DNA damage response (DDR) dysregulation, mutations in cell cycle regulators, and altered signaling pathways

Difference between direct and indirect gene regulation

Direct regulation involves a molecule, like a transcription factor, binding directly to a DNA sequence to activate or repress gene expression. Indirect regulation, on the other hand, occurs when a molecule changes the activity of other regulatory factors, which then influence the target gene

CHip sequencing

A method used to identify and locate specific DNA-binding sites of proteins, such as transcription factors and histone modifications, within a genome

Positive feedback in autoregulation

An auto activator amplifies gene expression, Positive feedback can promote oscillations, which can be important for processes like embryonic development.

Negative feedback in autoregulation

An auto repressor attenuates gene expression, Negative feedback loops are crucial for maintaining a stable internal environment, keeping factors within a normal range.

Haploid

Is the number of chromosomes in each gamete (23) but is only one sister chromatid half

Diploid

Is when there is a whole sister chromatid a whole chromosome

Homologous chromosome

Homologous chromosomes are paired chromosomes in a diploid cell, with one chromosome inherited from each parent

Sister chromatid

A sister chromatid is one of the two identical copies of a chromosome that are produced during DNA replication

Allele

One of two or more versions of a genetic sequence at a particular region on a chromosome. An individual inherits two alleles for each gene, one from each parent.

Locus/loci

The specific physical location of a gene or genetic marker on a chromosome (An address for a gene)

Ploidy

The number of complete sets of chromosomes in a cell, and hence, the number of possible alleles for genes

Descent with modification

The concept that living organisms have evolved from common ancestors over time, with each subsequent generation inheriting traits from their predecessors, while also exhibiting modifications or changes in those traits.

Allele

A variant in a DNA of a gene

Heterozygous

An individual having two different alleles of a particular gene or genes, and so giving rise to varying offspring

Homozygous

Having two identical alleles of a particular gene or genes

Test cross

A test cross is a mating used to determine the genotype of an individual exhibiting a dominant phenotype, especially when the genotype is unknown

True/pure breeding

Organisms consistently pass on specific traits to their offspring, resulting in a predictable phenotype for those traits

Outcome of a single gene genetic cross

Known as a monohybrid cross, the expected outcome is a 3:1 phenotypic ratio in the F2 generation when both parents are heterozygous

Results of mitosis

Two diploid cells that are genetically identical to parent cell

Results of meiosis I

Two diploid cell with 2n= 4 chromosomes

Result of meiosis II

Four haploid cells with n=2

What happens during meiosis I

Crossing over in late prophase, Independent assortment in metaphase I, One round of chromosome replication, Two rounds of cell division (Meiosis I and II)

Nondisjunction in In meiosis I and II

Does not separate equally, Meiosis I is homologous chromosomes while Meiosis II is sister chromatids

Mendel's principle of segregation

During the formation of gametes, the two alleles for each gene separate from each other so that each gamete contains only one allele

Independent assortment

How different genes independently separate from one another when reproductive cells develop

How meiosis produce genetic variation

Crossing over, Independent Assortment, Allows for multiple variations of genes

Primary sex determining mechanisms

Primary sex determination is primarily governed by chromosomal mechanisms, particularly the presence or absence of the Y chromosome. In humans and many other mammals, the presence of a Y chromosome triggers the development of male characteristics, while its absence leads to female development. This is primarily due to the SRY gene on the Y chromosome (develops testes)

Dosage compensation in organisms

Dosage compensation can increase or decrease gene expression and can also shut down the entire chromosome (it regulates the chromosome expression)

Chromosome X inactivation result too and why

It is catrostopic because it cause methyl groups to increase within DNA and cause for the Chromosome to inactivate

Dominance

Is when no other phenotypes show and it is only that one

Codominance

Co-dominance is when both characteristics show

Incomplete dominance

The heterozygote is halfway between homozygous phenotypes

Allelic series

The order of dominance within alleles

Sex chromosomes do males and females have in an X-Y system

Males have XY (heterogametic), females have XX (homogametic).

How is the X chromosome passed from parent to child

Mothers pass an X to all children; fathers pass an X to daughters and a Y to sons

Sex-linked characteristic

A trait associated with a gene located on a sex chromosome.

X-linked characteristic

A trait caused by a gene on the X chromosome.

Y-linked characteristic

A trait caused by a gene on the Y chromosome; only males inherit it.

Hemizygous

Having only one copy of a gene, like males with X-linked genes.

Heterogametic sex

The sex with two different sex chromosomes (XY = male in humans).

Homogametic sex

The sex with two of the same sex chromosome (XX = female in humans).

How do you diagram a cross involving an X-linked trait

Use Xᴬ or Xᵃ for alleles and show inheritance through X and Y in Punnett squares

In a cross: XᴬXᵃ (female) × XᵃY (male), what genotypes/phenotypes are expected

25% XᴬXᵃ (carrier), 25% XᵃXᵃ (affected female), 25% XᴬY (unaffected male), 25% XᵃY (affected male)

Expected pattern for autosomal recessive inheritance

Can skip generations; affects both sexes equally; parents may be carriers

Expected pattern for autosomal dominant inheritance

Appears in every generation; affected individuals have at least one affected parent

Expected pattern for X-linked recessive inheritance

More common in males; affected males often have carrier mothers

Expected pattern for X-linked dominant inheritance

Affected fathers pass it to all daughters, not sons; both sexes can be affected

Expected pattern for Y-linked inheritance

Passed only from father to son; only males affected

How can you analyze a pedigree for an X-linked trait

Look for male-only inheritance patterns and carrier females passing the trait

Single-gene inheritance

Inheritance controlled by one gene, often showing predictable Mendelian ratios

Two-gene inheritance

Inheritance involves two different genes, which may assort independently or interact

Why are single- and two-gene inheritance patterns considered predictable

Because they often follow Mendel's laws (segregation and independent assortment)

Can phenotypes always be predicted by genotype

Phenotypes can be influenced by gene interactions, environment, or other factors

Example of a straightforward inheritance pattern

A monohybrid cross resulting in a 3:1 ratio in the F2 generation

inherited genes not show expected phenotypes

Due to incomplete dominance, codominance, epistasis, or environmental effects

Epistasis

When one gene masks or modifies the effect of another gene