Study guide

1. I-Viruses and Bacteria- Chapter 19
1. Describe the basic structure of a virus
a. A virus is a microscopic infectious disease that is unable to reproduce outside a host cell.
Each virus consists of genetic material, RNA or DNA, within a capsid, a protective protein
coat. This coat allows a virus to enter a host cell by using proteins that bind to the
receptors on the surface of a cell and “trick” the cell.
2. What are common shapes of viruses?
a. There are four shapes of viruses, Spaceship, Rod, Ball and the Dodecahedron
3. Describe how a virus enters a cell and reproduces. Use lytic and lysogenic in your answer.
Watch videos, really helpful
a. Lysogenic Infection: http://www.youtube.com/watch?v=_J9-xKitsd0
i. Bacteriophage injects DNA into bacterium
ii. Bateriophage DNA forms a circle
iii. Bacteriophage DNA inserts itself into bacterial chromosome
iv. Bacteriophage DNA may replicate with bacterium for many generations
v. Bacteriophage DNA can exit the bacterial chromosome. Bacteriophage enters
the lytic cycle
vi. Bacteriophage takes over the bacterium’s metabolism causing the synthesis of
new bacteriophage proteins and nucleic acids
vii. Bacteriophage proteins and nucleic acids assemble into complete bacteriophage
particles.
viii. Bacteriophage enzyme lyses the bacterium’s cell wall releasing new
bacteriophage particles that can attack other cells
b. Lytic Infection: http://www.youtube.com/watch?v=wVkCyU5aeeU
i. Bacteriophage injects DNA into bacterium
ii. Bacteriophage DNA forms a circle
iii. Bacteriophage takes over the bacterium’s metabolism causing the synthesis of
new bacteriophage proteins and nucleic acids

2. iv. Bacteriophage proteins and nucleic acids assemble into complete bacteriophage
particles.
v. Bacteriophage enzyme lyses the bacterium’s cell wall releasing new
bacteriophage particles that can attack other cells
4. Are bacteria unicellular or multicellular? Are they prokaryotic or eukaryotic?
a. Bacteria are both unicellular and multicellular but most are unicellular.
b. Bacteria are prokaryotic.
5. What are the common shapes of Bacteria?
a. There are 3 common shapes
i. spirili- spiral shaped
ii. cocci- round shaped
iii. bascilli- rod shaped
6. What are antibodies?
a. A blood protein produced in response to and counteracting a specific antigen.
They are help in destroying pathogens.
7. What are disinfectants?
a. A chemical liquid that destroys bacteria.
8. What are antiseptics?
a. A substance that inhibits the growth and reproduction of disease-causing
microorganisms.
9. Describe each process for inhibiting bacterial growth: pasteurization, dehydrating, freezing and
canning.
a. Pasteurization
i. A method of treating food by heating it to a certain point to kill pathogenic
organisms but not harm the flavor or quality of the food.
b. Dehydrating
i. A method of preserving food by removing all water and liquids from the agent.
c. Freezing
i. A method of preserving food by subjecting it to freezing temperatures.
d. Canning
i. A method of preserving food by sealing food in cans or tins.
10. What is a vaccine?
a. A preparation of weakened or killed pathogens that is used to stimulate antibody
production and immunity against the pathogen.
11. What is an endospore?
a. A resistant asexual spore that develops inside some bacteria cells
12. Describe interferon.
a. A protein released by animal cells, usually in response to the entry of a virus, that
has the property of inhibiting virus replication
13. Describe “Koch’s Postulates”
a. Koch’s Postulates are a set of rules that are used to identify the microorganism
that causes a specific disease
i. He created 4 criteria for his postulates

3. 1. The bacteria must be present in every case of the disease.
2. The bacteria must be isolated from the host with the disease and
grown in pure culture.
3. The specific disease must be reproduced when a pure culture of the
bacteria is inoculated into a healthy susceptible host.
4. The bacteria must be recoverable from the experimentally infected
host
II- DNA, RNA and Protein Synthesis- Chapter 12
1. What is the shape of a DNA molecule?
a. Double helix
i. Looks like a twisted ladder
2. Describe the structure of a DNA molecule.
a. It is a right handed double helix. It is made up of nucleotides that are bound to each
other by hydrogen bonds. It consists of a phosphorous group, and deoxyribose
sugar, and a base (Adenine, Guanine, Cytosine, Thymine) The bases are
"connected" to each other by hydrogen bonding. A::T G:::C each colon represents
the number of H bonds.
3. Describe how nitrogen bases pair
a. Adenine binds to Thymidine
b. Cytosine binds to Guanine
4. What nitrogen base does an RNA molecule have in place of thymine?
a. Uracil
5. Describe transcription. Include mRNA in your answer and describe that molecule.
a. http://www.youtube.com/watch?v=WsofH466lqk
i. Transcription is the process in which mRNA molecules are produced by copying
a nucleotide sequence of DNA and making a complementary sequence of
mRNA.
ii. During transcription RNA polymerase binds to DNA and separates DNA strands.
RNA polymerase then uses one strand of DNA as a template from which
nucleotides are assembled into a strand of mRNA.
6. Describe translation. Include tRNA in your answer and describe that molecule.
a. http://www.youtube.com/watch?v=5bLEDd-PSTQ
i. Translation is the decoding of an mRNA message into a protein.
ii. During translation proteins are made using the codes from amino acids. the
codes for these amino acids are found in the nucleus and need to be
transferred into the ribosomes where proteins are made. mRNA is able to
carry this information and transfers it to the ribosome. RNA then sticks to the
ribosome which then allows for all the amino acids which connect with the
certain combinations of nucleotides to make proteins.
iii.

4. 7. What role do amino acids play in protein synthesis?
a. Proteins are simply chains of amino acids. Ribosomes produce proteins by chaining
these amino acids in correspondence to the codons on the mRNA.
III- Genetics and Punnett Squares- Chapter 11
1. What is a gene?
a. A sequence of DNA that codes for proteins and determines traits.
2. Describe dominant and recessive in relation to allele pairs.
a. An allele is the different forms of a single gene.
i. A dominant allele (for example) in a pea is the color green
ii. The recessive allele in a pea would be yellow
3. Describe how an organism can be heterozygous for a trait.
a. An organism that has two different alleles for the same trait would be heterozygous.
i. For example: Tt Qq
4. How can an organism be homozygous for a trait?
a. An organism that has two identical alleles for a particular trait would be
homozygous.
i. For example: TT qq
5. Describe genotype.
a. Genetic makeup
i. The actual alleles that make up its genes.
6. Describe phenotype.
a. Physical characteristics
i. The physical characteristics as a result of the genotype.
7. What does independent assortment mean?
a. The principle of independent assortment states that genes for different traits can
segregate independently during the formation of gametes.

5. 8. What does co-dominance mean?
a. When the alleles of a gene pair result in a phenotype that is neither dominant nor
recessive.
i. For example:
a. Dominant: black
b. Recessive: White
c. Codominant: Black and white stripes
IV- Evolution- Chapter 15
1. Described acquired characteristics. Who is associated with this term?
a. A characteristic of an organism that results from increased use or disuse of an organ
i. Jean Baptiste Lamarck
2. Describe natural selection. Who is associated with this term?
a. The process where organisms better adapted to their environment survive and
produce more offspring, passing their traits to the next generation.
i. Charles Darwin
3. Describe adaptation.
a. An inherited characteristic that increases an organism’s chance of survival.
4. What are homologous structures?
a. Structures that have different mature forms but develop from the same embryonic
tissues.
5. What are vestigial organs?
a. An organ that has no particular function or use.
i. For example: the appendix
V- Classification- Chapter 18
1. For this section just look at the chart on page 459