Unit 3

James Watson and Francis Crick

(took a lot of credit for Franklins work) Used all the former findings to build a model of the double helix DNA molecule.

By recognizing the mechanisms through which organisms change over time, or evolve, we gain insight into which of the following?

- How to design better medications such as antiviral agents and vaccines - Resistance to insecticides and antibiotics - How the organization of life on our planet reflects evolutionary history

Erwin Chargaff (1950)

- Identified the pattern of nucleotide base-pairing. - Identified that the percent of Adenine in a DNA molecule equaled that of Thymine, and the percent of Guanine always equaled Cytosine.

Pedigree

- Males are designated by squares and females by circles. - Shaded circles and squares represent individuals expressing the genetic trait of interest. - A line between a square and a circle represents a union and vertical lines represent the children of that union. - Specific individuals in a pedigree may be identified by generation (numbered down the left side).

DNA Molecule

- The nucleotide base pairs between DNA strands are linked by hydrogen bonds. - Double helix - In a DNA molecule, %A = %T and %G = %C

Why is the influenza virus a good model for the study of evolution?

- The virus reproduces rapidly. - The genetic material of influenza changes quickly. - The virus is responsible for a human disease.

stabilizing selection

- favors most common form of variant for the trait - selection occurs against the extreme variants - the average individuals are most adapted to the environment - the population distribution narrows toward the average

Biologists use five characteristics to determine if something is considered alive or not. These include the ability to:

- process energy and materials - maintain an internal environment - respond to stimuli from the environment - reproduce - adapt to changing environmental conditions

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

incomplete dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

Virus

A tiny, nonliving particle that invades and then reproduces inside a living cell.

Homologous chromosomes contain similar genes, but often different alleles.

After replication, sister chromatids contain identical allele combinations.

genetic marker

Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder

Biological systematics

An area of biology that studies biological diversity and the evolutionary relationships of organisms

Ecology

An area of biology that studies how organisms have evolved to fill their roles within an ecosystem

reverse transcriptase

An enzyme encoded by certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.

Genetic Markers

An inheritance of a variation in the pattern of DNA nucleotide means that a person may be susceptible for a certain disease

Haploid

An organism or cell having only one complete set of chromosomes. (n)

Autosomes

Any chromosome that is not a sex chromosome (first 22)

homologous chromosomes

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.

Alfred Hershey and Martha Chase (1952)

Conducted an experiment with a virus called bacteriophage. - The virus used had either radioactively labels DNA or protein. - By tracking where the radioactive isotopes ended up after the viruses infected the cells, they identified that DNA, not protein that resulted from DNA, is the genetic material in cells.

Direct DNA Sequencing

Determining the exact sequence of nucleotides, scientists are able to identify specific alleles associated with a disease

Examples of genetic diseases

Down syndrome, sickle-cell anemia, cystic fibrosis, Tay-Sachs disease, etc.

During which of the following is genetic information introduced into the cells that will become the gametes?

Genetic information introduced into the cells that will become the gametes during prophase I of metaphase.

Allele

Genetic variation of a gene

DNA Microarrays

Identifies a specific allele or patterns of gene expression between two cell types, tissues, or individuals

Which of the following statements are true concerning evolution? (select all that apply)

It is the unifying theme in the study of biology and it is the result of heritable changes in the DNA.

Meiosis

Meiosis is a form of cell division that reduces the chromosome number of the daughter cells from haploid to diploid, and introduces variation into the daughter cells. It consists of two rounds of cell division, and results in the formation of four haploid cells

Are genetic diseases curable?

No

sex chromosomes

One of the 23 pairs of chromosomes in the human, contains genes that will determine the sex of the individual.

ex vivo gene therapy

Process occurs outside of the body; Stem cells are removed from the bone marrow, mixed with a normal gene, inserted into a vector, and reintroduced into the bone marrow of the patient.

Erasmus Darwin

Proposed that evidence from animal development and animal breeding shows that species may evolve over time

Charles Lyell

Proposed that the Earth's surface is dynamic and constantly changing

Georges Cuvier

Proposed the idea of catastrophism; he believed that all species were created at the same time, yet catastrophic events have caused some species to go extinct and studied the fossil record and noticed that fossils showed a succession of different forms of life over time

Jean-Baptiste Lamarck

Proposed the idea referred to as inheritance of acquired characteristics

Which of the following statements is correct regarding sexual reproduction?

Spermatogenesis produces four haploid sperm cells during meiosis.

Inheritance

The process in which genetic material is passed from parents to their offspring.

Oogenesis

The production of mature egg cells.

Which of the following statements are correct concerning the influenza A virus?

The virus uses H and N spikes to target its host cell.

Why do we use rats in experiments?

Their DNA is very similar to humans.

Sister chrimatids

Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle.

If an individual with type A blood marries a person with type AB blood, which blood types may be present in their offspring?

Type B Type A Type O Type AB

Rosalind Franklin

Used X-Ray crystallography to examine the structure of DNA molecules. - Her experiments led to the realization that DNA is a double helix.

chorionic villus sampling

a sample of fetal cells are collected from the region where the placenta will develop

Natural selection causes mutations.

false

All viruses have

genetic material and capsid

lysogenic cycle

it can integrate directly into the host cell genome and delay its own reproduction until a later time

Gene

segment of DNA that contains instructions for the production of a protein

Mutations are constantly occurring in the genetic material.

true

Mutations represent the source of genetic variation in a population.

true

gene expression

what gene is "turned on" or shown. (Blue eyes vs Brown eyes but brown eyes are expressed)

disruptive selection

- Changes in the environment cause the average variant to be detrimental - the population distribution will favor the variants at the ends of the distribution, splitting the distribution into two peaks.

directional selection

- Changes in the environment direct natural selection to favor the variation at one end of the distribution. - the population distribution of the trait shifts toward the extreme.

Select all of the characteristics that are considered to be evidence of natural selection that Darwin observed aboard the Beagle.

- Collecting fossilized remains of extinct animals along the west coast of South America challenged Darwin's idea that the Earth was young. - In regard to biogeography, Darwin discovered similar environments and animals with similar appearances in South America and Europe. - Collecting fossilized remains of extinct animals along the west coast of South America, Darwin believed that all species were created at the same time and did not change form. - Darwin noted that unique island finch species are descendants from the mainland species that have developed adaptations to survive on the island's food source.

Life Cycle of the HIV Virus

- HIV is an RNA virus, it must convert its genetic information into DNA using an enzyme called reverse transcriptase. Once done, biosynthesis of new viral proteins can begin. - Unfortunately, the reverse transcriptase enzyme is not always efficient in copying the RNA into DNA, and it introduces mistakes, or mutations, that cause variations in the new viruses.

Which of the following circumstances are necessary for evolution to occur? Select all that apply.

- Variation for a particular trait exists within a population. - A particular trait must be able to be passed on to the next.

Capsid

A protein coat that surrounds the genetic material. The capsid may have proteins attached to it, such as tail fibers or spikes, that assist the virus in attaching to the target host cell.

in vivo gene therapy

A type of gene therapy in which the correct gene is injected directly into the body; the vector with the functioning gene is injected into an area and genes are changed in the cells still in the body

Genetics

An area of biology that studies how genetic material changes over time

Viruses' genomes may use either ___ or ___ as their genetic material.

DNA or RNA

Which of the following is a component of a virus? (select all that apply)

DNA or RNA, Capsid

Which of the following processes determines the precise order of nucleotides in a gene of interest?

DNA sequencing DNA microarrays Polymerase chain reaction Karyotype

Gregor Mendel

Developed law of segregation: - Each individual has for each trait two factors and these factors separate (segregate) during the formation of the gametes (meiosis). - Each individual has two factors for each trait (meaning it is diploid), but it produces gametes that have only one factor for each trait (haploid). - Fertilization produces a new individual with two factors for each trait (diploid).

A DNA molecule has the codons TACGATTTTGCA. Using the genetic code, what is the sequence of amino acids that would be expressed by this code?

Met-Leu-Lys-Arg

semiconservative replication

Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand

How Are Flu Viruses Named?

On the surface of an influenza A virus are two different types of spikes. These spikes are a type of glycoproteins (a protein with a sugar attached) that assist the virus in identifying and entering its host cell

Mutations

Random errors in gene replication that lead to a change in the sequence of nucleotides. The source of all genetic diversity. - Ex: sickle-cell diseases

One cell in our entire body that does not contain genetic material:

Red blood cells (do not have nucleus)

Oswald Avery (1944)

Repeated Griffiths experiment but added the enzyme DNase. - DNase breaks down DNA molecules and when DNase was present, the transformation of the R strain did not occur and the mice lived. - The results suggest DNA was the genetic material.

Which of the following is not involved in the process of transcription?

Ribosomes DNA Messenger RNA (mRNA) RNA polymerase

DNA is replicated during

S phase of interphase

Thomas Malthus

Stated that populations sometimes increase at rates faster than their food supply can increase, thus creating competition

Chromosome structure

The DNA double helix is first wrapped around proteins called histones to form nucleosomes. Nucleosomes are then further condensed to form chromosomes.

Genetic Material

The genetic material, which may be in the form of DNA or RNA, contains a relatively small number of genes in comparison to a cell.

Natural selection favors variation, which increases the ability of the individual to reproduce and pass the trait on to the next generation, and acts against detrimental traits.

True

Frederick Griffith (1928)

Used pneumonia-causing bacteria in mice to indicate a transforming facor could move information between strains. 1) Injected live S stain has capsule into mice and mice die. 2) Injected live R strain has no capsule into mice and they do not die. 3) Injected heat-killed S strain and mice do not die. 4) Injected heat-killed S strain plus live R strain and mice die. Live S strain in withdrawn from mice.

Karyotype

Visualizing an individual's autosomes and sex chromosomes to determine if there are any changes on the chromosomes

sickle cell disease

a mutation in the beta-globin genes causes the normal glutamine amino acid (Glu) to be replaced by a valine (Val) amino acid.

How are genetic diseases caused

a mutation in the genetic information of an individual that can be passed down generations

Amniocentesis

a sample of amniotic fluid from the uterus of a pregnant woman is collected by passing a long needle through the abdominal and uterine walls in order to collect fetal cells.

codon

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

Which of the following ingredients in an influenza vaccine helps the immune system identify the flu virus?

aluminum salts

start codon

codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein (AUG)

stop codon

codon that signals to ribosomes to stop translation (UAA,UAG,UGA)

Chromosomes

composed of DNA and packaging proteins called histones. Each cell with a nucleus in the body can have up to 2 meters of DNA (about 6.5 feet!). Because most cells are microscopic, the DNA needs to be tightly packaged into a smaller structure to fit within the nucleus of the cell.

lyctic cycle

immediately begin using the resources of the host cell to manufacture new viruses

Influenza virus

influenza A, B, C, and D. Of these, influenza A and influenza B are the two most prevalent forms of the virus that infect humans. - influenza virus requires epithelial cells that line our respiratory system in order to reproduce.

PCR is a technique used in the laboratory to ___.

make millions of copies of a gene of interest.

Evolution is described as the change in heritable traits of a(n) __________ over a period of time.

population

Which of the following methods of producing a vaccine does not require the use of the entire influenza virus?

recombinant method

Crossing over

recombines the genetic information from the two homologous chromosomes, and produces new combinations of alleles not present in the original chromosomes

Gametes

sex cells

Once the virus has entered the target cell, there are two pathways, or cycles, it can follow:

the lytic cycle or the lysogenic cycle

Spermatogenesis

the production of sperm cells

All cells in our body (except RBC) contain

the same genetic material

Diploid

we have two copies of each chromosome: one we inherited from our mother, and one from our father (2n)