Biology B Final Exam

Review

Explain the purpose of DNA replication and the steps

involved. Where in the cell does it occur?

Purpose: Ensure that the resulting replicated

cells each have a complete and exact copy of the original cells genome (genes)

So that the daughter cells function like the parent cells

Where it occurs: Nucleus

Steps for DNA Replication

1. Double helix unwinds

2. Strands separate

3. Free floating DNA nucleotides are bonded to the parent strands by DNA Polymerase (enzyme)

Describe the functions of the 3 types of RNA. Be able to identify them in a diagram. Where in the cell are they

located and where are they synthesized?

mRNA (messenger): Copies information from

DNA in the nucleus

rRNA (ribosomal) Makes up the ribosome Made in the nucleolus

tRNA (transfer): Transfers amino acids in

the cytoplasm to the ribosome

Compare/contrast DNA vs. RNA (where in the cell each type is found;

the subunits and molecules that make up each subunit).

DNA RNA

Location Nucleus mRNA: Nucleus and CytoplasmrRNA: RibosometRNA: Cytoplasm

Number of strands

2 1

Nucleotide Phosphate group

Deoxyribose sugar

A, T, G, C

Phosphate group

Ribose sugarA, U, G, C

Which nitrogen bases are found in DNA? In RNA?

DNA: Adeni

ne Thym

ine Guani

ne Cytos

ine

RNA: Adeni

ne Uraci

l Guani

ne Cytos

ine

Which nitrogen bases form complimentary pairs in

DNA? In RNA? DNA

A=T G=C

RNA A=U G=C

What is the purpose of transcription? Describe the steps involved and where in the cell it takes place. Be able to

label a diagram of the process. Purpose:

Copy information from DNA in the form of mRNA so that it can be brought to the ribosome to build the protein

Steps:1. Specific sequence of DNA unwinds and

separates2. RNA polymerase (enzyme) adds

complementary RNA nucleotides to one strand of DNA

3. When complete, mRNA breaks away from the DNA and leaves the nucleus

4. The DNA winds back up

What is the purpose of translation? Describe the steps involved and where in the cell it takes place. Be able to

label a diagram of the process. Purpose:

Translate the mRNA sequence at the ribosome to build the protein

Steps:1. mRNA leaves the nucleus for the ribosome.2. Once there, the ribosome exposes the

codon on mRNA3. tRNA with the amino acid that is coded for

by the codon, transfers the amino acid to the ribosomea. Codon matches with the anticodon

4. tRNA continues adding amino acids until ribosome reaches stop codon – Makes a polypeptide (Protein)

Know how to use a mRNA codon chart.

What does GCU on mRNA

code for? What is

the codon for

tyrosine?

GCU = Ala

Tyrosine = UAU, UAC

What is a gene?

Sequence of DNA that codes for a specific protein

What makes proteins different from one another? What determines which specific protein is to be produced? Differences in proteins:

Sequence of amino acids

Determines differences: Sequence of nitrogen bases in DNA

What are mutations? What kinds of effect can mutations

have on an organism? Mutation:

Changes in one or more nitrogen bases on DNA or RNA

Effect: Change the sequence of amino acids

coded for by the DNA/mRNA Create a defective protein Result in an adaptation No effect

What are mutagens? Give 3 examples.

Mutagen: Something that can cause a

mutation (change in the DNA or RNA sequence)

Examples: X-ray UV light Chemicals Radioactive substances

What causes one cell to have a different function than

another cell?

All cells in a single organism have the same DNA/genes

Differentiation of cells results from activation of different genes Some genes are “turned off”

GENETIC TECHNOLOGY (13.2)

What is recombinant DNA?

DNA from two different sources that has been combined

Example: Plasmid DNA

What can be produced agriculturally from recombinant DNA?

1. Glowing tobacco plants2. Plants resistant to insects3. Bigger produce, animals4. Drought resistant plants

How is genetic engineering (biotechnology) used to

produce biomedical products such as insulin?

1. Gene of interest is cut out of the DNA of an organism – Ex. insulin

2. Gene from one organism can be inserted into a plasmid (vector) – Recombinant DNA

3. Plasmid is then inserted into a bacteria

4. Bacteria will use the foreign gene to make insulin

EVOLUTION (14.1, 15.1, 15.2)

What does the geological time scale

show? Be able to analyze and

determine the chronological order of

organisms.

Geological time scale shows the major events in Earth’s history in chronological order

What explains the disappearance of fossils from one era/period/rock

layer to the next?

Extinction – if the fossil no longer appears in rock layers following where it was found, then there is a good chance that it became extinct

How do fossils form? How can you determine the age of a fossil? (2 ways)

How Formed? Sediment

1. Organism dies2. Buried under layers of

sediments3. Soft tissue

decomposes, bones/hard parts are left behind

4. Pressure fossilizes the bone

Ice Amber Trace Mold Cast

Age of a Fossil:

Relative Dating Where in the rock layers

the fossils reside

Absolute (radiometric dating)

Measuring the amount of radio active isotopes is still present

What observations did Charles Darwin make in regards to various species found on the Galapagos Islands?

Each species had adaptations specific for the island that they live

What are the principles of Darwin’s theory of evolution? Organisms overproduce Variation exist among

populations Organisms compete for

resources Variations are inherited Those with the better

adaptations survive and pass on genes

Natural Selection Define natural selection according to Darwin.

Organisms with the more favorable variations (differences) have an increased chance of survival and reproduction

How do genetics, variation, and environment play a role in natural selection? Natural selection acts on the genes – organisms that

survive pass on their genes to offspring

What does his theory of evolution suggest? How does natural selection relate to evolution? Organisms best fit for the environment pass on their

genes

What does natural selection specifically act on? Variations and genes

Define speciation. Describe the processes that allow new species to be formed. How do you know when a new species has formed?

Speciation: The development/evolution of a new species

Process: Geographic isolation Reproductive isolation Mutation

How Know: Species can no longer interbreed (cannot

produce viable offspring)

What is the difference between geographic

isolation and reproductive isolation?

Geographic isolation: Species are separated by a barrier

(Ex: mountain, large river) Do not interbreed

Reproductive isolation: Species are different because of

reproductive structures or behaviors (mating seasons, calls)

Do not interbreed

Geographic Isolation

Reproductive Isolation

How can organisms become “resistant” to things like

pesticides, antibiotics, etc? When a pesticide or antibiotics is used, it

will generally kill most organisms off

A select few will survive Survivors have resistance in their genes

The survivors will reproduce and a majority of the population will be “resistant”

How can scientists determine whether two different species came from a common/related

ancestor? Homologous structures: same structure,

different function

Embryological similarity: similar structures as an embryo

Molecular homology: DNA and gene similarity (biochemistry)

Homologous Structures

Embryology

Define genetic drift. What is a gene pool? Describe what happens to a gene pool (benefits and consequences) when

genetic drift occurs. How can lethal alleles be maintained in a gene pool? Genetic Drift – When a random mutation (or alelle) is

found within a population that isolated itself from the general population – change in allele frequency

Gene Pool – collection of all of the alleles in the population

When genetic drift occurs: Specific traits become more prevalent within the

population Can be dominant or recessive

Ex. Tay Sachs, Polydactyly

Lethal Alleles are maintained (kept in the population) because individuals can be carriers for the bad allele (Ex. Tay sachs, cystic fibrosis, sickle cell)

What causes evolution to occur more quickly in a

population?

Population is small Isolated Many Mutations

HUMAN BODY SYSTEMS: Nervous (36.1, 36.3), Immune (39.1, 39.2),

Endocrine (35.3), Skeletal (34.2), Muscular (34.3),

Digestive (35.1), Respiratory (37.1),

Circulatory (37.2), Urinary (37.3)

What are the major functions of each system? What are the major

organs within each system and what are their specific functions?

Nervous System: Processes information, controls every process

Immune System: Build up resistance to disease Endocrine System: Releases hormones to

maintain growth, metabolism, and homeostasis Digestive System: Break down nutrients from

food Circulatory System: Distribute blood, oxygen,

nutrients throughout the body Respiratory System: Exchange oxygen and

carbon dioxide in cells Skeletal and Muscular System: Support and

movement of the body Exocrine: Dispose of waste (urine, sweat)

What is the relationship between one system and each of the other systems? How does each system work with the other systems? For example, be able

to explain what systems would work together in order for you to be able to jump or talk? to

maintain homeostasis? to respond to stimuli? breathe? digest food?

SEE INTERACTION CHART

Describe the function and structure of a

neuron. Function:

Receive and send chemical/electrical signals from outside environment

Nervous System (36.1, 36.3) and Endocrine System (35.3)

What are the three types of neurons?

1. Sensory Neuron: a. Receive signals

2. Interneuron:a. Brain and spinal

cordb. Process info

3. Motor neuron: a. Do response

What is an impulse?

Path that signals in the nervous system take

Pathway: Senses Sensory neuron interneuron (brain) motor

neuron – muscle (movement)

How do drugs affect the transmission of an impulse?

Drugs can slow down response time

They interfere with the passing of signals from one neuron to another

Compete with neurotransmitters for receptors on neurons

Explain how a feedback loop (negative feedback system)

works.

Immune System (39.1, 39.2, 34.1, 18.1, 18.2)

What is the body’s first line of defense? Second line? First Line of Defense

Barriers Inflammation

Second Line of Defense Cell Mediated Response: T cells cytotoxic T

cells Humoral Response: B cells antibodies

How does immunity occur? How does the immune system respond to

antigens?

1. Macrophage engulfs a pathogen

2. Activates T helper cella. T helper cell activates B cell

i. B cell makes antibodies ii. Makes memory cells

b. T helper cell activates cytotoxic T cell

i. Cytotoxic T cell destroys infected cells

ii. Makes memory cells

What are pathogens, antibodies, antigens?

Pathogen: Disease causing substance

Antigen: Foreign substance in the body

Antibodies: Proteins that the immune system uses to find and attach to pathogens and antigens

What is the function of white blood

cells? Identify

antigens

Break down and remove antigens

B cells – make antibodies

T cells – Destroy infected cells

What are the functions antibodies?

Antibodies are released by B cells

Bind to antigens

Signal Macrophages to digest antigen

Compare/contrast viruses vs. bacteria (characteristics). How does each one “work” once it infects the body? How

do you treat the illnesses that each one produces? What are some effective

defenses against each one?Viruses Bacteria

How infects Uses a host cell Produces toxins

Treatment Run course or antivirals

Antibiotics

Defenses Vaccines Anti-microbials

How does HIV affect the immune system?

Attacks and uses Helper T cells to make more HIV viruses

Helper T cells activate the immune system

What is AIDS? What can result from this disorder?

Acquired Immunodeficiency Syndrome When the number of T

cells drops below a certain number

Individual dies from opportunistic infections

Infections that are usually easily defended against with a healthy immune system