Transcript Module B Review

Module B Review
2nd Quarterly Assessment Review
Units 6 & 7
BIO.B.1.2
• Explain how genetic information is inherited.
• Describe how the process of DNA replication
results in the transmission and/or
conservation of genetic information.
• Explain the functional relationships between
DNA, genes, alleles, and chromosomes and
their roles in inheritance.
What is the relationship between a
chromosome, a gene, and a nucleus?
DNA
• There are 4 types of nitrogenous bases: thymine, adenine, cytosine,
and guanine
• The nitrogen containing bases are the only difference in the four
nucleotides.
Proteins carry out the process of
replication.
• DNA serves only as a template.
• Enzymes and other proteins do the actual
work of replication.
• Process
1. Enzymes unzip the double helix.
2. Free-floating nucleotides form hydrogen bonds
with the template strand.
nucleotide
The DNA molecule
unzips in both directions.
3. DNA polymerase enzymes bond the nucleotides
together to form the double helix.
1. Sugar
Phosphate
Backbone
4. new strand
2. Nitrogen bases
3. DNA polymerase
4. Two new molecules of DNA are formed, each with an original strand and
a newly formed strand.
• DNA replication is semi-conservative, meaning one original strand
and one new strand.
• The information is conserved, or kept the same because each side
always serves as a template (always using the same information).
original strand
Two molecules of DNA
new strand
BIO.B.2.2
• Explain the process of protein synthesis (i.e.,
transcription, translation, and protein
modification).
• Describe how the processes of transcription
and translation are similar in all organisms.
• Describe the role of ribosomes, endoplasmic
reticulum, Golgi apparatus, and the nucleus in
the production of specific types of proteins.
• RNA RNA differs from DNA in three major ways.
– DNA has a deoxyribose sugar, RNA has a ribose sugar.
– RNA has uracil instead of thymine (found in DNA)
– A pairs with U
– DNA is a double stranded molecule, RNA is single-stranded.
TRANSCRIPTION & TRANSLATION: To make a protein from DNA using
RNA.
start site
transcription complex
5. nucleotides
6. RNA
codon for
codon for
methionine (Met)
leucine (Leu)
• Translation aka: Protein Synthesis
• Both Prokaryotes & Eukaryotes can carry out
protein synthesis because they both have
ribosomes.
Describe how the processes of transcription and translation
are similar in all organisms.
Both prokaryotes and eukaryotes have DNA and
follow the same base pairing rules, so they both can
change DNA into RNA. The big difference here is that
Eukaryotes carry out transcription in the nucleus,
prokaryotes carry it out in the cytoplasm because
they have NO nucleus.
Translation occurs at the site of a ribosome. Since
both cell types have ribosomes, ALL living things go
through translation aka protein synthesis.
• https://www.youtube.com/watch?v=K2_uB7ybfYM
Transport Using Organelles
How does the rough ER work with the Golgi?
Nucleus – Ribosome (RER) – Transport Vesicle – Golgi Body –
Secretory Vesicle
• Vesicle: Small membrane-bound sacs that divide some materials
from the rest of the cytoplasm and transport these materials
within the cell.
• Proteins (such as secretory & membrane proteins) made by
ribosomes on the rough ER are packaged in vesicles and sent to the
cell membrane or Golgi Apparatus.
• The Golgi Body processes & sorts the proteins, then packages them
into vesicles for storage, transport, or secretion from the cell
membrane.
Transport of materials
• Vesicle: Small membrane-bound sacs
that divide some materials from the rest
of the cytoplasm and transport these
materials within the cell.
• Proteins (such as secretory & membrane
proteins) made by ribosomes on the
rough ER are packaged in vesicles and
sent to the cell membrane or Golgi
Apparatus.
• The Golgi Body processes & sorts the
proteins, then packages them into
vesicles for storage, transport, or
secretion from the cell membrane.
• BIO. B.2.1: Describe processes that can alter composition or
number of chromosomes (i.e., crossing over, nondisjunction,
duplication, translocation, deletion, insertion, and inversion).
• BIO.B.2.3 : Explain how genetic information is expressed.
• Describe how genetic mutations alter the DNA sequence and
may or may not affect phenotype (e.g., silent, nonsense, frame
shift).
Some mutations affect a single gene,
while others affect an entire chromosome.
A gene mutation affects a single gene.
• Many kinds of mutations can occur, especially
during replication.
Types of Gene Mutations:
• A point mutation substitutes one nucleotide for
another. Ex: Sickle Cell Anemia
mutated
base
Nonsense Mutation
• Type of point mutation
• Results in a premature stop codon and
usually a nonfunctional protein
• A frame-shift mutation inserts or deletes a nucleotide in the DNA
sequence. Throws off the reading frame.
• THE CAT ATE THE RAT
• THC ATA TET HER AT
• Chromosomal mutations affect many genes
and an entire chromosome. Chromosomal
mutations may occur during crossing over.
Deletion
 Due to breakage
 A piece of a chromosome is lost
Inversion
 Chromosome segment breaks off
 Segment flips around backwards
 Segment reattaches
•
Translocation results from the exchange of DNA (piece of one chromosome)
segments between non-homologous chromosomes.
Nondisjunction
 Failure of chromosomes to separate
during meiosis
 Causes gamete to have too many or
too few chromosomes
Nondisjunction
 Can cause “Trisomy” (three copies of the same
chromosome in an egg or sperm)
 Trisomy 21 (Down syndrome)
• Gene duplication results from unequal exchange of segments crossing
over. Results in one chromosome having 2 copies of some genes and the
other chromosomes having no copies of those genes.
Several methods help map human
chromosomes.
• A karyotype is a picture of all chromosomes in a cell.
XY
BIO.B.2.4
• Apply scientific thinking, processes, tools, and
technologies in the study of genetics.
• Explain how genetic engineering has impacted
the fields of medicine, forensics, and
agriculture (e.g., selective breeding, gene
splicing, cloning, genetically modified
organisms, gene therapy).
9.1: Manipulating DNA
• Key Concept:
– Biotechnology relies on cutting DNA at specific
places.
Restriction sites
A DNA fingerprint is a type of restriction
map.
• DNA fingerprints are based on parts of an individual’s DNA
that can be used for identification
– Based on noncoding regions of DNA
– Noncoding regions have repeating DNA sequences
– Number of repeats differs between people
– Banding pattern on a gel is a DNA fingerprint
DNA fingerprinting is used for
identification. Use in forensics
• DNA fingerprinting depends on the probability of a match.
– Many people have the same number of repeats in a
certain region of DNA
– The probability that two people share identical numbers of
repeats in several locations is very small (only one chance
in over 5 million people that they would match)
– Several regions of DNA are used to make a DNA
fingerprint.
Uses of DNA Fingerprinting (Forensics
& Agriculture)
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Evidence in criminal cases
Paternity tests
Immigration requests
Studying biodiversity
Tracking genetically modified crops
Cloning
• A clone is a genetically identical copy of a gene
or an organism
• Cloning occurs in nature
– Bacteria (binary fission)
– Some plants (from roots)
– Some simple animals (budding, regeneration)
Pros/Cons of Cloning
Benefits
• Organs for transplant into
humans
• Save endangered species
• Reproduce beneficial traits
Concerns
• Low success rate
• Clones “imperfect” and less
healthy than original animal
• Decreased biodiversity
Genetic Engineering/Gene Splicing
• Involves changing an organism’s DNA to give it new traits
• Based on the use of recombinant DNA
– Recombinant DNA contains DNA from more than one
organism
(bacterial DNA)
Uses of Genetic Engineering
• Transgenic bacteria can be used to produce
human proteins
– Bacteria can be used to produce human insulin for diabetics
(Use in Medicine)
• Transgenic plants are common in agriculture
– transgenic bacteria infect a plant
– plant expresses foreign gene
– many crops are now genetically modified
(GM)
– Increase nutrient levels in crops like rice
• Gives them traits like resistance to frost, diseases,
insects
• Increase crop yield – more food quickly and cheaply
• Transgenic animals are used to study diseases and gene functions
(Medicine)
Concerns about GMO’s
– Possible long-term health effects of eating GM foods.
• Allergies?
– Possible effects of GM plants on ecosystems and
biodiversity
• Lack of genetic diversity in transgenic plants could leave them
vulnerable to new diseases or pests.
• Effects on natural plant pollinators like bees and butterflies.
• Cross pollination between transgenic plants and natural plants.
Selective Breeding/Artificial Selection
• is the process by which humans use animal
breeding and plant breeding to selectively
develop particular phenotypic traits
(characteristics) by choosing which typically
animal or plant males and females will
sexually reproduce and have offspring
together.
Unit 7 BIO.B.3.1, BIO.B.3.2
BIO.B.3.3
• Explain the mechanisms of evolution.
• Explain how natural selection can impact allele frequencies of a
population.
• Describe the factors that can contribute to the development of new
species (e.g., isolating mechanisms, genetic drift, founder effect,
migration).
• Explain how genetic mutations may result in genotypic and phenotypic
variations within a population.
• Analyze the sources of evidence for biological evolution.
• Interpret evidence supporting the theory of evolution (i.e., fossil,
anatomical, physiological, embryological, biochemical, and universal
genetic code).
• Apply scientific thinking, processes, tools, and technologies in the study of
the theory of evolution.
• Distinguish between the scientific terms: hypothesis, inference, law,
theory, principle, fact, and observation.
Evolution
• The theory that proposes that different kinds
of living organisms are thought to have
developed and diversified from earlier forms
during the history of the earth.
Darwin observed differences among island
species.
• Variation: difference in a physical trait
– Galapagos tortoises that live in areas with tall plants have long necks and long
legs
– Galapagos tortoises that live in areas with low plants have short necks and short
legs
– Galapagos finches (Darwin’s finches) that live in areas with hard-shelled nuts have
strong beaks
– Galapagos finches that live in areas with insects/fruit have long, thin beaks
• Adaptation: feature that allows an
organism to better survive in its
environment
–Adaptations can lead to
genetic change in a population because those that can
survive better will pass on their specific traits and the
population in later years will be full of those traits.
Unfavorable traits will decrease over time.
Several key insights led to Darwin’s idea
for natural selection.
• Natural selection: mechanism by which
individuals that have inherited beneficial
adaptations produce more offspring on average
than do other individuals
• Heritability: ability of a trait to be passed down
• There is a struggle for survival due to
overpopulation and limited resources
• Darwin proposed that adaptations arose over
many generations
Fossils & the Fossil Record
• Shows how species changed their form/shape over
time
• Ways of dating fossils:
– Relative dating: estimates the age of fossils by comparing
fossil to others in the same layer of rock
• Pro: can be used if there is no other way to tell the age of the fossil
• Con: layers of rock can be shifted by natural events (earthquakes,
mudslides, etc.) and this can mess up estimate
– Radiometric dating: uses the decay of radioactive isotopes
(carbon-14 changes into carbon-12)
• Pro: can give an accurate age
• Con: can’t give an age for really old fossils (if all isotopes have
decayed)
Biogeography
• Island species most closely resemble
nearest mainland species
• Populations can show variation from one
island to another
• Example: rabbit fur vs. climate
Embryology
• Similar embryos,
diverse organisms
• Identical larvae,
diverse adult body forms
• Gill slits and “tails”
as embryos
Larva
Adult crab
Adult barnacle
Anatomy: Homologous Structures
• Similar in structure, different in function
• Evidence of a common ancestor
• Example: bones in the forelimbs of different
animals (humans, cat legs, whale fins, bat wings)
Anatomy:Vestigial Organs/Structures
• Remnants of organs or structures that had a
function in an early ancestor but have lost their
function over time
• Evidence of a common ancestor
• Examples:
– Human appendix & tailbone
– Wings on flightless birds (ostrich, penguins)
– Hindlimbs on whales, snakes
Molecular Biology (DNA/Proteins)
• Common genetic code (A, T, C, & G)
• Similarities in DNA, proteins, genes,
& gene products
• Two closely related organisms will
have similar DNA sequences & proteins
11.1 – Genetic Variation Within
Populations
• Key Concept:
– A population shares a common gene pool.
Directional Selection
• Favors phenotypes at one extreme
Stabilizing Selection
• Favors the intermediate phenotype
Disruptive Selection
• Favors both extreme phenotypes
Gene Flow/Migration
• Movement of alleles between populations
• Occurs when individuals
join new populations
and reproduce
• Keeps neighboring
populations similar
• Low gene flow
increases the chance
that two populations
will evolve into different
species
bald eagle migration
Genetic Drift
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Change in allele frequencies due to chance
Causes a loss of genetic diversity
Common in small populations
Bottleneck Effect is genetic
drift after a bottleneck event
– Occurs when an event
drastically reduces population size
• Founder Effect: is genetic drift that occurs after the
start of a new population
– Occurs when a few individuals
start a new population
Sexual selection occurs when certain traits
increase mating success.
• Sexual selection
– Occurs due to higher cost of reproduction for females
• Males produce sperm continuously
• Females are more limited in potential offspring each cycle
– Two types:
• Intrasexual selection: competition among males
• Intersexual selection: males display certain traits to females
Isolation
• If gene flow stops between two populations, they are
said to be isolated.
• Adaptations, mutation, and genetic drift may change
the gene pools of the populations, and over time the
populations may become more and more genetically
different. (Changes genotype and therefore phenotype)
• Reproductive isolation/Post-Zygotic: when members of
different populations can no longer mate successfully
with one another. (Ex: fruit fly mutation leads to a
different pheromone) also called sympatric isolation
– This is the final step before speciation (the rise of two or more species
from one existing species)
Isolation
• Several kinds of barriers can prevent mating between
populations, leading to reproductive isolation. These
are all known as pre-zygotic isolation.
• Behavioral isolation: differences in courtship or mating
behaviors. (Different song)
• Geographic isolation: physical barriers that divide a
population into two or more groups. (See pic) also
called allopatric speciation.
• Temporal isolation: timing prevents reproduction
between populations. (Different pollination times in
trees)
Benefit to Isolation
• Gives rise to new species
• Adds more diversity on Earth.
Species can become extinct.
• Extinction: elimination of a species from Earth
– Background extinction
– Mass extinction
1.3: Scientific Thinking &
Processes
Key concept: Science is a way of
thinking, questioning, and gathering
evidence.
BIO.B.3.3
• Apply scientific thinking, processes, tools, and
technologies in the study of the theory of
evolution.
• Distinguish between the scientific terms:
hypothesis, inference, law, theory, principle,
fact, and observation.
• Science is a process of trying to understand the
world around us using critical and logical thinking
to evaluate results and conclusions.
• Scientists gather evidence and share their
findings with one another.
• Observation: the use of our senses, computers,
and other tools to gather information about the
world.
– Ex.: Studying the interactions between gorillas by
observing their behavior.
Observations can be recorded as data
to be analyzed
• Qualitative data: Descriptions of phenomena
that can include sights, sounds, and smells.
• Quantitative data: Characteristics that can be
measured or counted such as mass, volume,
and temperature; Numbers
Scientists use observations and data to
form hypotheses
• Hypothesis: A proposed, testable answer to a
scientific question.
– Formal hypotheses are usually written in an “if,
then, because” format.
– If (change of IV) then (change of DV) because (why
you think this will happen).
How do scientists test hypotheses?
• The scientific method
– A) Observe and ask questions that lead to a problem
– B) Form a hypothesis
– C) Test the hypothesis with a controlled experiment by
making observations and gathering data.
– D) Analyze gathered data
– E) Reject (start over at step B) or Accept your
hypothesis.
– F) Form a conclusion
How do scientists test hypotheses?
• Controlled experiments study the effect of
independent variables on dependent variables.
• Independent variable: A condition that is
manipulated, or changed, by a scientist. Effects
are measured by changes in dependent variables.
• Dependent variable: observed and measured
during an experiment.
– Example: Testing medication to treat blood pressure.
IV: medication dose, DV: blood pressure.
Controlled experiments
• Only one independent variable should be
changed in an experiment.
• Other conditions must stay the same and are
called constants.
• Controlled experiments must have a control
group – everything is the same as the
experimental groups but the independent
variable is not manipulated.
– Example: When testing blood pressure medication,
control group receives none of the active ingredient.
• A large number of test subjects or trials is ideal.
Other important science terms
• Inference: A conclusion reached on the basis of evidence and
reasoning. (Ex: you make an inference when you use clues to figure
something out).
• Law: A law that generalizes a body of observations. At the time it is
made, no exceptions have been found to a law. It explains things but
does not describe them; serves as the basis of scientific principles.
(Ex: Law of Gravity, Newton’s Laws of motion).
• Theory: A proposed explanation for observations and experimental
results that is supported by a wide range of evidence – may
eventually be accepted by the scientific community. (Ex: Big Bang
Theory, Evolution & Natural Selection)
• Principle: A concept based on scientific laws and axioms (rules
assumed to be present, true, and valid) where general agreement is
present. (Ex: Buoyancy Principle)
• Fact: An observation that has been repeatedly confirmed.