Download Support for Evolution

Essay Exam Review_2015-05
1. Describe Mendel’s laws of inheritance. (10.2)
The Inheritance of Traits
Mendel’s law of segregation
• The law of segregation states that the two alleles for each trait
separate during meiosis.
• During fertilization, two alleles for that trait unite.
• Heterozygous organisms are called hybrids.
The Inheritance of Traits
Law of independent assortment
•
The law of independent assortment states that random distribution
of alleles occurs during gamete formation.
•
Genes on separate chromosomes sort independently during
meiosis.
•
Each allele combination is equally likely to occur.
2. Distinguish between incomplete and codominance.
(11.2)
Complex Inheritance Patterns
In incomplete dominance, the heterozygous phenotype is
intermediated (inbetween) between two homozygous
phenotypes.
Complex Inheritance Patterns
In codominance, both alleles are expressed in heterozygotes.
3. Describe the structure of DNA. You may also include a
sketch of the DNA molecule to help, however there
must be written description of the molecule. (12.1)
DNA Structure
Nucleotides
•
Nucleotides are the subunits of nucleic acids, and consist of
• 5-carbon sugar
• Phosphate group
• Nitrogenous base
DNA Structure
DNA structure
•
DNA often is compared to a twisted ladder.
• Rails of the ladder are represented by the alternating deoxyribose
and phosphate.
• The pairs of bases (cytosine-guanine or thymine-adenine) form the
steps.
•
Purine base always binds to a pyrimidine base
DNA Structure
Orientation
•
DNA molecules have specific orientations of the two strands
• One of the strands is said to be oriented 5’ to 3’.
• The other strand runs in the opposite direction and is oriented 3’ to
5’.
4. Describe what is meant by semiconservative
replication. (12.2)
Semiconservative Replication
•
During semiconservative replication, parental strands of DNA separate,
serve as templates, and produce DNA molecules that have one strand of
parental DNA and one strand of new DNA.
•
Process occurs in three main steps: unwinding, pairing, and joining.
Semiconservative Replication
Unwinding
•
DNA helicase, an enzyme, unwinds the helix, breaking the hydrogen bonds
between bases
•
Single-stranded binding proteins keep the DNA strands separate during
replication.
•
RNA primase adds short segments of RNA primer, on each DNA strand.
Semiconservative Replication
Base pairing
•
The enzyme DNA polymerase adds appropriate nucleotides to the new DNA
strand from the 3’ end.
•
The leading strand is built continuously, the lagging strand is built
discontinuously in small segments called Okazaki fragments.
Semiconservative Replication
Joining
•
DNA polymerase removes the RNA primer and fills in the place with DNA
nucleotides.
•
DNA ligase links the two sections.
5. Describe the process of protein synthesis. (12.3; see
Fig.15, p. 339)
6. Compare outcomes of mutations that occur in bodycells with those of mutations that occur in sex-cells.
(12.4)
Mutations
Types of mutations
•
•
•
A permanent change that occurs in a cell’s DNA is called a mutation.
Point mutation: involve chemical change to just one base pair
• Missense substitutions: DNA codes for the wrong amino acid
• Nonsense mutation: Codon for amino acid becomes a stop codon
Insertion/deletion: additions/ loss of a nucleotide to the DNA sequence
• Cause “frameshifts”
Mutations
Causes of mutation
•
•
Can occur spontaneously – DNA polymerase can attach the wrong
nucleotide, but this is rare and usually corrected.
Certain chemicals and radiation called mutagens can damage DNA.
• Chemicals can cause mispairing of base pairs, or themselves
substitute for base pairs.
• High-energy radiation can eject electrons from atoms within the DNA
molecule, leaving behind unstable free radicals.
Mutations
Body-cell v. sex-cell mutation
•
•
Somatic cell mutations are not passed on to the next generation.
Mutations that occur in sex cells are passed on to the organism’s offspring
and will be present in every cell of the offspring.
7. What is endosymbiont theory? And, what is the
evidence that supports this theory? (14.2)
Cellular Evolution
The endosymbiont theory
•
Lynn Margulis proposed the endosymbiont theory, which proposed that
ancestral eukaryotic cells absorbed prokaryotic cells, which evolved into
organelles.
• Prokaryotes entered eukaryotic cells as undigested food or parasites.
• Their relationship became mutually beneficial.
• The theory explains the double membranes around mitochondria and
chloroplasts.
8. Explain the four principles of the theory of natural
selection. (15.1)
Developing the Theory of Evolution
Natural selection
•
Principles of natural selection:
• Individuals show variation
• Variations are heritable
• More offspring are born than can survive
• Variations that increase reproductive success will be more common in
the next generation
9. There are five lines of evidence that support
the scientific theory of evolution. List all five
AND explain two of them. (15.2)
Support for Evolution
•
Evidence for evolution comes from:
• The fossil record
• Comparative anatomy
• Comparative embryology
• Comparative biochemistry
• Geographic distribution
Support for Evolution
The fossil record
•
Fossils show modern species resemble ancient species.
•
They also reveal that some species have changed very little.
•
The fossil record is an important source of information for determining the
ancestry of organisms and the patterns of evolution.
Support for Evolution
The fossil record
•
Darwin predicted the existence of fossils intermediate in form between
species, such as Archaeopteryx.
•
Researchers consider two major classes of traits when studying transitional
fossils:
• Derived traits are newly evolved features, such as feathers, that do not
appear in the fossils of common ancestors.
• Ancestral traits are more primitive features, such as teeth and tails, that
do appear in ancestral forms.
Support for Evolution
Comparative anatomy
•
Anatomically similar structures inherited from a common ancestor are called
homologous structures.
•
Evolution predicts that an organism’s body parts are more likely to be
modifications of ancestral body parts than entirely new structures.
Support for Evolution
Comparative anatomy
•
Vestigial structures are structures that are the reduced forms of functional
structures in other organisms.
•
Evolutionary theory predicts that features of ancestors that no longer have a
function for that species will become smaller over time until they are lost.
snake pelvis
human appendix
Support for Evolution
Comparative anatomy
•
Analogous structures can be used for the same purpose and be superficially
similar in construction, but are not inherited from a common ancestor.
•
Analogous structures show that functionally similar features can evolve
independently under similar conditions.
Support for Evolution
Comparative embryology
•
An embryo is an early, pre-birth stage of an organism’s development.
•
Vertebrate embryos exhibit homologous structures during phases of
development that become totally different structures in the adult forms.
The explanation for this similarity in embryos is a shared history of
vertebrates—all vertebrates share a common ancestor that had a tailed
embryo with gill pouches
Support for Evolution
Comparative biochemistry
•
Common ancestry can be seen in the complex metabolic molecules that
many different organisms share.
•
The more closely related species are to each other, the greater the
biochemical similarity.
Support for Evolution
Geographic distribution
•
The distribution of plants and animals that Darwin observed were what first
suggested evolution to him.
•
The distribution of plants and animals around the world is studied in the field
of biogeography.
•
Evolution is linked to migration
patterns, climate, and
geological forces (such
as plate tectonics).
10. Explain the concept of genetic drift. Include
explanations of two specific types of genetic drift.
(15.3)
Mechanisms of Evolution
Population genetics
•
For a population to be in genetic equilibrium (which means NOT evolving)
according to the Hardy-Weinberg principle, it must meet five conditions:
1. No genetic drift
2. No gene flow
3. No mutation
4. Mating must be random
5. No natural selection
•
These five conditions are the mechanisms of evolutionary change.
Mechanisms of Evolution
Genetic drift
•
•
Any change in the allelic frequencies in a population that results from
chance is called genetic drift.
In smaller populations, the effects of genetic drift become more pronounced,
and the chance of losing an allele becomes greater.
Mechanisms of Evolution
Genetic drift
•
The founder effect results when a group of individuals with a different allele
frequency than the original population becomes isolated.
• Alleles that were infrequent in the original population may be common in
the new population.
• Happens when a subset of organisms settles in an area separated from
their original population
• Can result in large genetic variations in the separated population
Mechanisms of Evolution
Genetic drift
•
•
A bottleneck results when population declines to a very low level and then
rebounds.
The gene pool of the rebound population is similar to the low-level
population, which may have reduced diversity.
11. Using binomial nomenclature, describe how scientific
names are written. Give examples of scientific names
for humans and for the Northern Cardinal. (17.1)
Early Systems of Classification
Linnaeus’s system
•
Linnaeus’s system of classification was based on observations of
morphology and habitat.
•
The Linnaean system was the first formal system of taxonomy – the
discipline of identifying, naming, and classifying organisms.
Binomial nomenclature
•
Linnaeus’s method of naming organisms, called binomial nomenclature,
gives each species a scientific name with two parts.
•
The first part is the genus name, and the second part is the specific epithet,
or specific name, that identifies the species.
•
Biologists use scientific names for species because common names vary in
their use.
Early Systems of Classification
Binomial nomenclature
•
When writing a scientific name, scientists use these rules:
• The first letter of the genus name always is capitalized, but the rest of the
genus name and all letters of the specific epithet are lowercase.
• If a scientific name is written in a printed book or magazine, it should be
italicized.
• When a scientific name is written by hand, both parts of the name should
be underlined.
• After the scientific name has been written completely, the genus name
will be abbreviated to the first letter in later appearances (e.g., C.
cardinalis).
12. Describe the hierarchical scheme for classifying
organisms into taxonomic categories. (17.1)
Early Systems of Classification
Modern classification systems
•
Modern classification is rooted in the Linnaean system
•
As the study of evolution grew, scientists began using evolutionary
relationships in their classification systems.
Taxonomic Categories
•
The taxonomic categories used by scientists
are part of a nested-hierarchal system.
•
Each category is contained within another,
and they are arranged from broadest to most
specific.
Taxonomic Categories
Species and genus
•
A named group of organisms is called a taxon.
•
A genus is a group of species that are closely related and share a
common ancestor.
Family
•
A family is the next higher taxon, consisting of similar, related genera
Taxonomic Categories
Higher taxa
•
An order contains related families.
•
A class contains related orders.
•
A phylum or division contains related classes.
•
A kingdom contains related phyla.
•
The domain is the broadest of all the taxa and contains one or more
kingdoms.
13. Explain how to construct a cladogram. You may
sketch an example to go with your explanation (17.2)
Phylogenetic Reconstruction
Character types
•
Cladistics classifies organisms based on the order that they diverged
from a common ancestor.
•
Scientists consider two main types of characters when doing cladistic
analyses:
• Ancestral characters are found within the entire line of descent of a
group of organisms.
• Derived characters are only found after a split from the descendent
line.
Phylogenetic Reconstruction
Cladograms
•
A cladogram is a branching diagram that represents a proposed
phylogeny of a species or group.
•
One branch of a cladogram is called a clade.
Phylogenetic Reconstruction
Cladograms
•
To construct a cladogram, groups of
interest need to be compared to an
outgroup, which has more ancestral
characteristics.
•
The cladogram is constructed by
sequencing the order in which derived
characters evolved with respect to the
outgroup.
•
The more derived characteristics two
groups share, the more recently the
groups shared a common ancestor.
14. Distinguish between Archaea and Bacteria. (18.1)
Diversity of Prokaryotes
•
Prokaryotes are divided into two domains: Bacteria and Archaea.
•
Bacteria (eubacteria) belong to Domain Bacteria, exist in nearly every
environment on earth, important to human body, industry, and food
production.
•
Archaea tolerate extreme environments, have similar proteins to eukaryotic
cells.
Diversity of Prokaryotes
Bacteria
•
Cell walls contain peptidoglycan
•
Some have second cell walls
•
Some are photosynthetic
Diversity of Prokaryotes
Archaea
•
Predominate in extreme environments
•
Mostly anaerobic, cannot tolerate oxygen
•
Include halophiles (salt-loving), methanogens (use CO2 and give off
methane), and thermoacidiphiles (high temperature, low pH).
15. Why are viruses not considered part of the living
world? (Lesson 13, 17.3, and 18.2)
Domain Eukarya
Viruses – an exception
•
•
•
A virus is a nucleic acid surrounded by a protein coat.
Viruses do not possess cells, nor are they cells, and are not considered
to be living.
Because they are nonliving, they usually are not placed in the biological
classification system.
16. Briefly describe each of the levels of biological
organization found in a multicellular organism.
(Lesson 25)
17. Briefly describe what processes occur in each of the
following parts of the digestive system: mouth,
stomach, small intestine, and the large intestine.
(Lesson 27)
18. For plants, describe vascular tissue, and distinguish
between the two types of vascular tissue. (Lesson 30)
19. The Russian olive tree (Elaeagnus angustifolia) is an exotic invasive tree capable of
sexual reproduction. Sexual reproduction involves flowering, pollination, and
production of fruit that has seeds within. This species is also capable of asexual
reproduction. Briefly describe some of the different ways plants can reproduce
asexually. (Lesson 31)
20. Pick any other topic we learned about this year and
explain what your learned.