Genetics Chapter 1-6 Exam 1

What does gene knockout allow scientists to do?

Allows scientists to render genes nonfunctional to investigate the possible role of that gene

What do cell cycle checkpoints do?

Monitor for mitosis errors

What is the difference between discontinuous variation and continuous variation?

Discontinuous variation was suggested by Mendel that heredity resulted in a dominant/recessive relationship.

Continuous variation was suggested by Darwin and Wallace, who believed there were a blend of parental phenotypes

What two things influence the phenotypic expression of a trait?

The environment and genotype of the organism

What are the earliest examples of DNA markers?

RFLPs and micro-satellites

Explain the differences and similarities of lysing a cell and lysogeny

Both lysing a cell and lysogeny deal with a phage entering a bacterial host cell. Lysing a cell means the cell bursts after the phage has entered the bacterial host cell, releasing the phage. Lysogeny occurs when the phage DNA integrates into a bacterial chromosome and coexists with the other DNA of the bacterial host cell.

What is gene knockout?

When a scientist purposely inactivates a gene to. Investigate the role that the specific gene plays.

What is the role of separase and shugoshin?

Separase: degrade cohesion (protein that holds sister chromatids together

Shugoshin: protects cohesion from degradation by separase

Differentiate continuous and discontinuous variation

Continuous: blend of parental phenotypes

Discontinuous: dominant/recessive relationship/traits

What is pleiotropy?

Expression of one gene has many phenotypical effects

True or false: Sister chromatid exchanges occur during meiosis and produce new allelic combinations

False

What is passed from the F+ cell to the F- cell in conjugation with a sex pious in bacteria?

The F+ cell will convert the F- recipient into an F+ cell after the DNA has moved into the F- cell

______ allows scientists to render genes nonfunctional to investigate the possible role of that gene.

Gene knockout

What are the steps of mitosis in eukaryotic cells? Include the first step right before mitosis.

Interphase, prophase, prometaphase, metaphase, anaphase, telophase

What is the difference between homozygous and heterozygous alleles?

Homozygous: identical alleles (GG, gg)

Heterozygous: two different alleles (Gg)

Phenotypic expression of a trait is influenced by _________.

Environment, genotype, biological sex

Which DNA marker is generated by cutting DNA with restriction enzymes?

RFLPs

What are the three types of horizontal gene transfer?

Conjugation: sex pilus cell-to-cell DNA transfer

Transformation: uptake of DNA from environment

Transduction: transfer via bacteriophages

What is the difference between forward and reverse genetics?

Forward genetics: when you are looking to identify the gene that caused mutant phenotype

Reverse genetics: when you are looking to identify the phenotype caused by the known DNA sequence of a gene

True or false: Homologous Chromosomes are identical

False, they are similar but not identical

What is Mendel’s three postulates?

1. Unit factors (genes) exist in pairs

2. Dominance/Recessive

3. Segregation

What is pleiotriopy?

When 1 gene expression leads to many phenotypic effects

What are the differences between complete, negative, and positive interference?

Complete: no double crossovers occur

Negative: more double crossovers occur than expected

Positive: less double crossovers occur than expected

Does lysogeny cause lysis of the host?

No

What is the Theory of Epigenesis?

Theory stating that structures, such as body organs, are not initially present in the early embryo. These structure development later in embryonic development.

What are the 6 main stages of the cell cycle (in order)

Interphase, prophase, prometaphase, metaphase, anaphase, tekophase

What is continuous variation?

The idea that there is a blend of the parental phenotypes in offspring

What is epistasis?

Expression of one gene masks or modifies the phenotypic effect of another gene

What is crossing over? What type(s) of gametes are produced as a result?

Crossing over is the process of two nonsister chromatids wrapping around each other during meiosis, forming an X shaped intersection. This process produces both recombinant and parental gametes

What is the function of the Cas proteins in CRISPR-Cas Immunity?

Cas proteins store pieces of phage DNA as a form of memory of infection

What characteristics are beneficial when selecting model organisms for genetical testing?

Easy to take care of, short life span, easy to track genetics, produces lots of offspring

Summarize the main groups of animals by splitting them between the categories: Prokaryotic and Eukaryoticf

Eukaryotic: animals, plants, fungi, protist

Prokaryotic: bacteria and archaea

When drawing a pedigree for a trait, many different symbols are used to indicate things. List these various options

Female - circle

Male - square

Parents - bracket

Two connected diagonal lines - monozygotic twins

Two connected lines with a small line connected - dizygotic twins

What is the key difference between Loss-of-function mutations and Gain-of-function mutations?

Loss-of-function mutations occur when an organism experiences a phenotypical change due to a change in activity/environment

Gain-of-function mutations occur when a mutation enhances the function of a wild-type genotype

When the distance between genes increases, what effect does the interference and mapping experience?

It experiences a decrease in the interference and mapping

What is the primary source of evolution in bacteria?

Spontaneous mutation

What is the Central Dogma of Genetics?

DNA —→ RNA ———> Protein

DNA get transcribed to RNA and RNA gets translated to Protein

What is the function of the endoplasmic reticulum? What are its two parts and what do they do?

The ER is an organelle that compartmentalizes cytoplasm and increases the surface area for biochemical synthesis. It has the smooth ER which is the site of fatty acid and phospholipid synthesis and the rough ER which is studded with ribosomes and is the site of protein synthesis

What are Mendel’s three postulates?

1. Genes exist in pairs

2. Idea of dominant/recessive

3. Paired genes segregate independently during gamete function

What is the difference between sex-limited inheritance and sex-influenced inheritance?

Sex-limited inheritance: expression of a specific phenotype that is absolutely one sex

Sex-influenced inheritance: when the sex of an individual influences the expression of a phenotypes but is not limited to one sex or the other

What is a DNA marker and why is it useful?

DNA marker: a short segment of DNA that has a known sequence and location. They are useful landmarks for DNA mapping

What is the difference between vertical and horizontal gene transfer?

Vertical gene transfer: transfer of genetic information between members of the same species

Horizontal gene transfer: transfer of genetic information between related but distinct species

Explain the chromosomal theory of inheritance and how it connects Mendel’s work to modern genetics

The theory states that genes are located on chromosomes and are transmitted through gametes from parents to offspring. This links Mendel’s ;was of inheritance to the behavior of chromosomes during meiosis which explains how traits are passed from generation to generation

What features are found in both eukaryotic and prokaryotic cells?

Plasma membrane, cytoplasm, ribosomes

Define the P, F1, and F2 generations

P: means the parental generation

F1: is the first generation of offspring parental generation

F2: is the second generation of offspring from the F1 generation

Differences between the Loss-of-function and the Gain-of-function

Loss-of-function: results in reduced or eliminated activity of the gene product, often producing a recessive phenotype

Gain-of-function: enhances the activity of the gene product or produces an entirely new function, often dominant

What does it mean when two genes are described as linked, and how does this affect their inheritance?

Linked genes are located on the same chromosome and therefore do not assort independently. They tend to be inherited together unless separated by crossing over during meiosis.

Why are bacteria and bacteriophages useful model organisms for genetic research?

They have short reproductive cycles, can be grown in pure culture, and allow genetic changes to be observed rapidly and effectively

What is the cell theory?

It is the theory that all organisms are composed of basic structural units called cells which was introduced by Schlieden and Schwann

What is the difference between the p and q arms of a chromosome?

The p arms are the small arms and the q arms are the long arms. Q arms are more likely to break during replication

In a pedigree what the symbols for gender, and how does a chart look including the possibility of twins?

Female - circle

Male - square

Parents - single horizontal line

Double line - parents are related

Twins - diagonal lines stemming from the vertical line that is connected to the parents

Monozygotic twins (identical) - diagonal lines directly from the parental generation and are connected to each other with a horizontal line

Dizygotic twins (fraternal) - diagonal lines directly from the parental generation and lack the connecting line

What influence the phenotypic expression of a trait?

The environment and the genotypic influence

Which of the following is NOT part of double crossover?

Double exchanges of genetic material

What is the difference between horizontal and vertical gene transfer?

Vertical gene transfer: transfer of genetic information between members of the same species, travels from parents to offspring

Horizontal gene transfer: transfer of genetic information between related, but distinct species which genes are moved between organisms of the same generation

What is a karyotype?

The physical appearance of all the chromosomes in a cell arranged in homologous pairs

What is a testcross? Why are they used?

A cross between an individual and a homozygous recessive individual. Used to determine if they are homozygous dominant or heterozygous for the trait

What is the Central Dogma of Molecular Biology?

DNA ——> RNA ——> Proteins

DNA gets transcribed to RNA and RNA gets translated into proteins

Which of these are not eukaryotic organisms?

A. Protists

B. Plants

C. Fungi

D. Archaea

Archaea

Describe Tay-Sach’s disease?

Recessive disorder that destroys the CNS. Tay-Sach’s lack the Hex-A enzyme causing physical impairment (long arms and legs hearing loss, vision loss) along with nerve cells and seizures

Describe the differences in recessive and dominant epistasis

Recessive: Homozygous recessive genotype at one locus masks the expression of another locua (aa or bb)

Dominant: Allele at one locus masks expression at second locus (Bb or BB)

What are restriction fragments and how are they useful in DNA markers?

Use restriction enzyme to cut out DNA sequences to analyze fragment lengths. RFLPs good at detecting heritable traits, unique fragment patterns for individuals

Describe phage life cycle

Absorption, penetration, replication, maturation, release

Phage is absorbed into the bacteria. Phage is inserted. DNA replicates/phage components are created. Mature phage assembled. Host cells are lysed and phage is released.

Compare and contrast genotype and phenotype

The phenotype is the trait that you can see in an organism

The genotype is the pair of alleles that make up a particular gene

How many cell divisions do mitosis and meiosis have?

Mitosis has one cell division through the steps of interphase, prophase, prometaphase, metaphase, anaphase, and telophase

Meiosis has two cell division through the steps of interphase 1, prophase 1, prometaphase 1, metaphase 1, anaphase 1, and telophase 1. Then the cell goes through everything a second time to go through the second division

What are Mendel’s 3 postulates?

Dominant/Recessive

Genes exist in 2 units

The paired genes separate independently during gamete formation

Define epistasis

Expression of one gene masking the effect of another gene; masking the phenotypic effect of another gene

What is the unit of genetic mapping?

Centi-Morgans (cM)

1% of recombination between 2 genes on a chromosome

Define bacteriophages

Viruses that infect bacteria and use them as their host

What is the structure of DNA?

DNA is antiparallel, double helix, and is nucleotide bound

What is the structure of RNA?

RNA is single stranded, has an alpha helix, U-A and C-G instead of T-A and G-C, is ribose bound

What features do all cells have?

DNA, plasma membrane, ribosomes

Define tetracross

Crossing of one trait

Define dihybrid cross

Crossing of 2 traits with 2 unique F2 generations

Define trihybrid cross

Crossing of three traits, each cross has a 62 box pedigree

What is a loss of function mutations?

Loss of function mutations: loss of wild type, new phenotypes results in changes in populations

What is a gain of function mutations?

Enhances wild type, resulting in increased genes in the population

Neutral mutations

No change in wild type, phenotype or fitness of organism

What is the relationship between the distance of two genes and the frequency of crossing over?

Crossing over is directly related to the distance between the two genes. If the genes are further apart there is less of a chance that those genes will cross and if the genes are closer together the more they are likely to cross over with each other.

What is the lytic life cycle?

Inject their genetic material into a host cell, hijack host replication operations, and replicate using host polymerase. When the viral life cycle concludes the phases lyse or burst out of the cell and cause cell death.

What is the lysogenic life cycle?

Lysogenic viruses integrate a template of their DNA directly into the host cell DNA. The genome of the virus remains latent in the genome and is passed onto daughter cells during cell division. When conditions are right the virus reactivates and causes cell lysis.

What are the three modern approaches to understanding gene function?

Classical forward genetics, reverse genetics, gene knockout

What is classical forward genetics?

Identifying the genes that caused mutant phenotypes

What is reverse genetics?

DNA sequence of a particular gene of interest is known, but its function is not

What is gene knockout?

Allows scientists to render gene nonfunctional to investigate the possible role of that gene

True or false: Chromosomes exist is heterologous pairs in diploid organisms

False: homologous

What is a phenotype?

The expression of a genotype

What are alleles?

Alternative forms of the same gene

What is a gene?

A unit of inheritance

What is a wild type allele?

Occurs the most common in nature but not always dominant

What is a linkage group?

Genes on the same chromosome

What is vertical gene transfer?

Transfer of genetic information within members of the same species

Explain how codons and proteins are related

Codons are triplet nucleotides that code for a specific protein.

An allele is different from a gene. (True or false)

True

What are Mendel’s three postulates

1. Recessive/Dominant

2. Unit factors exist in pairs

3. Segregation

What type of mutation results in a new phenotype and loss of wild-type function?

Loss of function

Bloom syndrome is caused by mutation BLM on chromosome 15. This causes increased frequency of sister chromatid exchange. This is an example of _____ chromosomes.

Harlequin

What is it called when bacteriophages reproduce via bacterial gene recombination?

Transduction

What are some characteristics of model organisms?

Easy to grow/keep alive, short life cycle, produce many offspring, and have straightforward genetic system

What stage of mitosis are cells in the majority of the time?

Interphase - this is where DNA is replicated

Heat is the difference between a dihybrid cross and a monohybrid cross?

Monohybrid: when there is just one trait with two possible alleles

Dihybrid: when there are two traits with two alleles each