Bio Lecture Exam 4 Review

Be able to determine the genotype of a plant when given terms: homozygous, heterozygous, dominant or recessive.

Homozygous Dominant: PP

Heterozygous Dominant: Pp

Homozygous Recessive: pp

Given the genotype of a plant, be able to determine all the types of gametes that this plant would produce.

Homozygous Recessive: two r gametes

Homozygous Dominant: two R gametes

Heterozygous Dominant: one R gametes and one r gamete

Be able to complete a monohybrid cross: Rr and RR

R R

R RR RR

r Rr Rr

What are two patterns of inheritance that do not follow Mendel’s laws?

Codominance and Incomplete Dominance

The calico pattern seen in some cats is a result of _____________.

X-inactivation

What does is mean to say that a gene is X-linked?

The gene is found on the X chromosome, and can affect both males and females.

What pattern of inheritance is a result of two o more genes being too close together on a chromosome and therefore do no assort independently?

Linkage

In what organelle(s) are extranuclear genes found?

The mitochondria and chloroplasts

What is epigenetic inheritance?

Modification of a gene during early development that may affect the phenotype of an individual, but does not alter the DNA sequence of the gene and it is not permanent over two or more generations

Which genetic cross would be predicted to give a phenotypic ratio of 9:3:3:1?

A dihybrid cross between two heterozygous genes. RrYy x RrYy

What is a pedigree analysis?

A family tree analysis of the results of mating which have occurred in the past that utilizes the principles of Mendelian inheritance

A cell has the ability to control its own level of gene expression; what is this called?

Gene regulation

Why is gene regulation necessary in Eukaryotic cells?

To conserve energy

Important for cell differentiation

Growth and development

Why do prokaryotic cells, such as bacterial cells, control their own level of gene expression?

In response to environmental changes (ex. Lactose rich environments)

What types of genes are always “on” and expressed at relatively constant levels in the cell?

Constitutive genes

(Remember Constant-Constit)

What type of genes are only expressed when needed in the cell in order to conserve energy?

Facultative genes

Be able to name 3 conditions that have to be met for a normal cell to divide.

All cells are favorable for cell division

All DNA and chromosomes are replicated and not damaged

All sister chromatids are attached to spindle fibers

Given the regions of a gene that can be affected by a genetic mutation, give an example of how a mutation in this region can impact gene expression(transcription/translation).

Regulatory region

Promoter region

Coding region

Regulatory region - if a mutation occurred in this region of the gene, the rate of transcription would be affected. Transcription would either increase or be inhibited.

Promoter region - RNA polymerase would either bind too tightly to the promoter (the rate/amount of transcription would be increased) or the enzymes would not be able to bind at all to the promoter (transcription would not occur).

Coding region - missence, nonsence, silent, or frameshift mutation could occur resulting in the wrong protein product.

Be able to discuss the difference between DNA mutations and DNA damage.

DNA mutations: occur randomly, can be beneficial harmful or neutral, cannot be fixed once the base pair change has occurred in both strands of the DNA

DNA damage: a physical abnormality in the DNA strand, can cause errors in replication, can be repaired by DNA Repair Systems

How does DNA damage relate to DNA mutations?

If DNA damage is not repaired it can lead to genetic mutations

What are the definitions of:

Silent mutation

Missense mutation

Nonsense mutation

Silent mutations: a mutation that does not alter the amino acid sequence of polypeptide, even though the nucleotide sequence has been changed

Missense mutation: a mutation results in a base substitution that changes a single amino acid in a polypeptide sequence

Nonsense mutation: a mutation that changes a codon, which would normally code for an amino acid, to a stop codon resulting in a shortened polypeptide being translated

Be able to match the following with its appropriate definition

Benign tumor

Malignant tumor

Metastatic tumor

Oncogene

Proto-oncogene

Benign tumor: tumor cells that have not invaded adjacent tissues

Malignant tumor: tumor cells that have invaded healthy tissue

Metastatic tumor: cancer cells that have migrated in the bloodstream

Oncogene: a gene that has the potential to cause cancer

Porto-oncogene: a normal gene that can be altered by mutation

Know the difference between a germ line mutation and a somatic mutation

Germ line mutation:

There is a mutation in the DNA of the gametes, either sperm or the egg

All the cells of the embryo will be affected

All the cells of the adult organism will be affected

Half of the gametes produced will carry the mutation, therefore the offspring could be affected

Somatic cell mutation:

There is not a mutation in the DNA of the gametes

The DNA within a single cell acquires a mutation

As that single cell divides, every daughter cell will carry the mutation. However, other cells will not

Gametes will not be affected, therefore the offspring will not be affected

What is an example of a missense mutation that we discussed in class?

Sickle Cell disease: sickle-cell disease is a result of a mutation whereby Glutamic acid is replaced by Valine resulting in red blood cells becoming sickled-shaped, fiber-like structures

What type of damage does UV light cause?

Thymine dimers

Can a mutation be repaired by DNA Repair system? If so, when?

Yes, but only if the repair is done in the first strand that acquires the mutation; once the base pair change has been made in both strands of the DNA, it can no longer be “‘fixed”

When are cancer cells said to be metastatic?

Metastatic cancer cells are those that have migrated to other parts of the body

Ex. Breast cancer in the brain

Tumor suppressor genes encode a protein product that helps to prevent tumors from forming. How can this function be lost?

Mutation

Chromosome loss

DNA methylation

Describe the Lytic cycle of a virus.

The Lytic cycle of a virus will result in the host cell being lysed to release new viruses. Intimately, the host cell will be killed.

Describe the Lysogenic cycle of a virus.

In the Lysogenic cycle of a virus, the virus will enter a latent, or dormant, phase. This cycle does not readily kill the host.

What is a virus?

A non-living particle that must be taken up by a living cell to replicate

What is a viroid?

A viroid is composed solely of single-stranded RNA; their genomes do not code for any proteins

What is a prion?

A prion is an infectious protein that causes a group rare fatal brain diseases

Be able to match the following plasmids with the genetic advantage they provide the bacterial cell:

Resistance Plasmid

Fertility Plasmid

Col-Plasmid

Degradative Plasmid

Virulence Plasmid

Resistance Plasmid: R factors - contain genes that confer resistance against antibiotics and other types of toxins

Fertility plasmids: F factors - allow bacteria to transfer genes to each other

Col-plasmids: contain gene that encode colicins (proteins that kill other bacteria)

Degradative plasmids: carry genes that enable the bacterium to digest and utilize an unusual substance

Virulence plasmids: gene that turns a bacterium into a pathogenic strain

How is it possible for prions to enter the bloodstream?

When contaminated meat is eaten, digestive enzymes in the stomach do not kill the prions; therefore they are then able to enter thee bloodstream

Does conjugation involve an equal distribution of genetic material from one bacterial cell to another?

No. In conjugation, only one bacterial cell transfers its genetic material to a receiving bacterial cell. The genetic exchange is not equal between the two cells involved in conjugation.

What is required for a bacterial cell to be transformed?

The transformation of a bacterial cell does not occur unless the bacterial cell in competent to take up genetic material from the surrounding environment. Transformation requires competent bacterial cells.

What type of chromosomes do bacterial cells contain?

Bacterial cells contains a single, circular chromosome that contains a few thousand genes. The chromosome is contained within the nucleotide region of the bacterial cell.

What are plasmids?

Plasmids are small circular pieces of DNA that exist separately from the bacterial chromosome. They provide some type of growth or survival advantage to the cell.

How many origins of replication does a bacterial chromosome have?

Bacterial chromosomes only contain one origin of replication

By what process can a virus cause a bacterial cell to become antibiotic resistant?

Transduction. The virus becomes the transducing phage.

By what process do bacterial cells reproduce?

Binary fission. This is also called Asexual reproduction and it results in the formation of 2 genetically daughter cells.

What are characteristics of bacterial gene transfer by conjugation?

Requires direct physical interaction

Does not involve equal genetic contribution

Does not produce offspring

Alters the genetic composition of the recipient cell

What is the capsid of a virus?

The protein coat that surrounds the viral genetic material

What are the characteristics of viral genomes?

Genetic material: RNA or DNA

Genomic structure: linear, circular, or segmented

Genomic size: >10,000 nucleotides - 1 million nucleotides<

Genomic segmentation

Evolution and classification

What was the first virus to be discovered?

The Tobacco Mosaic Virus

What defines many of the boundaries between geological time periods?

Mass extinction events where large number of species go extinct at the same time

How old is plant Earth?

4.5 billion years old

In which era did mammals become highly diversified and flowering plants become thee dominant plant?

Cenozoic Era

Which era saw the rise and fall of dinosaurs?

Mesozoic Era

Name two mechanisms responsible for the unity and diversity of life.

Vertical Decent with Modifications

Horizontal Gene Flow

What is Natural Selection?

The process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was was fully expounded by Charles Darwin and is now believed to be the email process that brings about evolution.

Whaat is natural selection based on?

Natural selection is based on the fitness of a phenotype.