Biology Exam 3 Spring Semester Fordham Lc

Front 1

You should be familiar with, and be prepared to diagram and discuss, the process of mRNA transcription. If given a base sequence in DNA you should be able to predict the mRNA sequence, and vice versa.

Back 1

Front 2

How does RNA differ chemically from DNA?

Back 2

Uracil instead of Thiamine

Front 3

Central Dogma of genetics (DNA TO Phenotype)

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Transcription and Translation of DNA to RNA to Protein

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What is the structure & function of transfer RNA?

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s RNA that transfers a specific active amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. tRNA has a 3' terminal site for amino acid attachment. This covalent linkage is catalyzed by an aminoacyl tRNA synthetase. It also contains a three base region called the anticodon that can base pair to the corresponding three base codon region on mRNA. Each type of tRNA molecule can be attached to only one type of amino acid, but because the genetic code contains multiple codons that specify the same amino acid, tRNA molecules bearing different anticodons may also carry the same amino acid.

Front 5

Translation proceeds through a sequence of steps (tRNA activation, initiation, elongation, termination). You should be familiar with, and be able to diagram and discuss each of these steps.

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Front 6

What are the roles of mRNA, tRNA, ribosomes, and amino acids in protein synthesis?

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DNA stores the genetic info. mRNA (Messenger RNA) transcribes that info. A ribosome comes along, and uses tRNA (Transfer RNA) to bring the appropriate amino acids together to make a protein. Peptide bonds are simply the bonds between the amino acids. Hence, proteins are a type of polypeptide.

Front 7

Chromosomal mutations?

Back 7

occur when the chromosome undergo crossing over during the process of meiosis. Due to this type of mutation, many parts of the DNA molecule get affected and abortion takes place if any genetic disease occurs in the baby. There are different types of chromosomal mutations:
1) Translocations:-
In this type, a piece of chromosome attaches to its non homologous part during crossing over. Translocation mutation can change the gene by breaking its real structure. Due to this the whole function of the gene changes. The disease of Leukemia occurs due to translocations between the chromosome 9 and 22. This hybrid gene creates a protein whose function is abnormal. Due to this abnormal gene, the normal growth of the cells stop and it ends up causing leukemia.

2) Inversions:-
If some region of DNA molecule changes its position on a chromosome, then inversions occur.

3) Deletions:-
Deletions cause the removal of a large part of the chromosome. Due to this, many genes are removed and the genetic material becomes mutated.

4) Duplications:-
When the genes appear more than once on the same chromosome, they result in duplications.

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What are the major kinds of point mutations?

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Point mutations occur when a single nucleotide is replaced with another nucleotide base. Insertion and deletion come in this category. Error in the process of replication of DNA molecule results in point mutations. Sometimes heat or high level radiations cause the error in DNA replication.
1) Nonsense mutations are the ones convert to stop codon.
2) Missense mutations occur in the genes which code for different amino acid.
3) Silent mutations do not affect the function of the proteins and code for different or same amino acid.

Front 9

What effect can mutations have on the decoding of the genetic message?

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can result in proteins being made at the wrong time or in the wrong cell type. Changes can also occur that result in too much or too little of the protein being made.

Front 10

Why are mutations generally harmful?

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mutations often lead to errors in reading the DNA. For example, the incorrect amino acid may be inserted in the polypeptide during translation. Or, the mutation may result in a stop codon, so the protein isn't fully formed. No/damaged proteins = cells can't carry out normal metabolism.

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What is the difference between a spontaneous and induced mutation?

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spontaneous mutations are caused by errors during DNA replication while induced mutations are caused by radiation(UV radiation, gamma radiation, etc.). Both types can lead to similar results.

Front 12

Viruses reproduce only when they infect living cells. Bacteriophages (viruses that infect bacteria) reproduce by a lytic cycle and a lysogenic cycle. Most viruses have their genes encoded in DNA but a smaller number of retroviruses (such as HIV) have RNA as their genetic material.

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Viruses reproduce only when they infect living cells. Bacteriophages (viruses that infect bacteria) reproduce by a lytic cycle and a lysogenic cycle. Most viruses have their genes encoded in DNA but a smaller number of retroviruses (such as HIV) have RNA as their genetic material.

Front 13

Although bacteria generally reproduce asexually, there are several ways that bacteria can acquire new genes. You should be familiar with the following processes: conjugation, transduction, transformation, and the acquisition of plasmids.

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conjugation- bacterial 'sex'
transduction- injection of foreign DNA by a bacteriophage into the host
transformation-acquisition of genetic extracellular genetic material
plasmid acquistion-DNA/RNA transfer by means of plasmid intake (F-factor)

Front 14

You should be able to discuss the techniques used to create a transgenic organism, esp. the roles of restriction endonucleases and the role of different kinds of vectors in transferring the gene to the target cells.

Back 14

methods- DNA microinjection, embryonic stem-cell meditated gene transfer and retrovirus-meditated gene transfer.

desired gene placed in vector(plasmid/virus), vector is treated with restction endonucleases, DNA recombinant takes place in sticky ends of endonucleases- bacteria produces desired protein.

Front 15

How can molecular biological techniques provide a treatment or possible cure for human genetic diseases (in vivo vs. ex vivo gene therapy methods)?

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Ex vivo- do transgenic operation w/ restriction endonucleases and vectors outside body, place back in, with use of stem cells.

In vivo- place recombinant DNA for certain protein production directly into the body.

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Recombinant DNA Gene Therapy

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Front 17

Recombinant DNA Gene Therapy

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Front 18

Types of Body Symmetry asymmetry, radial symmetry, bilateral symmetry);

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Types of Body Symmetry asymmetry, radial symmetry, bilateral symmetry);

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Types of Body Symmetry asymmetry, radial symmetry, bilateral symmetry);

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Body cavities

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Types of Body plans

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What are some of the major applications of recombinant DNA technology (bacteria, plants, animals)?

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growth hormone (rHGH), human insulin, follicle-stimulating hormone (FSH) and factor VIII. Other proteins, when used as medication, only has recombinant DNA as a source, such as with erythropoietin.

Front 24

You should be familiar with the major criteria used in animal classification-types of body cavities ; ,(protostome vs. deuterostome), and so forth.

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Body cavities- acoelomates, no cavity. pseudocoelomates semi-real cavity
(flatworm), coelomates, worms.

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Types of body symmetry

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asymmetry, radial, bilateral

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cleavage pattern, developmental mode

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spiral (frogs) vs radial cleavage (humans, echinoderms).

protostome- arthropods annelids, mollusks

deuterostomes- chordates, echinoderms

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Porifera

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Reproduce by budding/fragmentation, flagellated larvea, marine freshwater, no descendents, filterfeeder from external cells-water out the osculum.

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Cnidarians

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Hydrozoa (Hydra)-only endoderm/exoderm, reproduce by budding
Scyphozoa (Jellys)
Anthozoa (Anemone), also corals
Ctenophora (Comb jellies), glow in dark no nematocytes, planktonic.

polyp/medusa life cycle
tentacles have nematocytes-neurotoxins

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Platyhelminthes

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Flatworms, lophotrochozoans- skeleton internal, grow by adding size of skeleton.
1st w/ bilateral symmetry
-acoelomate
-incomplete gut
turbellaria, trematoda, cestoda

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Annelida

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segmented wroms
-coelomate
-bilateral
-complete gut
-oligochaeta-few segments
-polychaeta-many segments

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Mollusca

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Gastropoda (snail), bivalvia clams, cephalopoda (squid/octopus)
-coelum/segmentation reduced
-mantle (shell thing)
-similar to annelids in larval stage.

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Nematoda

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is an ecdysozoan.
-most abundant pseudocoelomates
-very common in all environments
-very tough cuticles
-free living/parasitic (trichonella)

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Arthropoda

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uniramia (Insects), chelicerates (horshoe crab/scorpion), crustaea (lobster/crab/barnacles),
-most diverse animal phylum
-bilateral symmetry
-complex nervous system
-compound eyes
-chitin exoskeleton

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Echinodermata

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Sea Urchin, starfish
-deuterostomes
-only marine

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Chordata

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-formation of notochord
-dorsal tubular nerve chord
-not all vertebrate( tunicate/sea squirt/lancelet) urochordate (tunicate) cephalochordate ( lancelet)
-Bony fishes
-amphibians-aquatic to terrestrial
-reptiles- sea turtle has lungs, reproduces on land.
Aves- evolve from reptiles, lack teeth, amniotic eggs.
mammals- prototherians(egg laying)
marsupial(pouch), euthendians (humans, etc..)

Front 36

Without genetic changes to a population, evolution would be impossible. Why?

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enetic change in a population from one generation to another. The speed and direction of change is variable with different species lines and at different times. Continuous evolution over many generations can result in the development of new varieties and species. Likewise, failure to evolve in response to environmental changes can, and often does, lead to extinction.

Front 37

The Hardy-Weinberg principle tells us that gene frequencies should reach equilibrium (i.e. remain stable) if certain assumptions are met. What are these assumptions?

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1. assume no mutations
2. assume infinite size populationa
3. no migration into or out of populaiton
4.no natural selection for any alleles
5. random mating

Front 38

Hardy Weinberg equation

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p^2+2pq+q^2
Aa- heterozygous alelle expression
p=freq A
q= freq a

p+q=1

Front 39

mutations and migration contribute to changes in gene frequencies in a population.

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mutations-occur in the genomes of organisms; these mutations create genetic variation. Mutations are changes in the DNA sequence of a cell's genome and are caused by radiation, viruses, transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication

migration- brings foreign alleles into/ out of population

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genetic drift

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Genetic drift or allelic drift is the change in the frequency of a gene variant (allele) in a population due to random sampling. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces. A population's allele frequency is the fraction of the copies of one gene that share a particular form.

A population bottleneck is when a population contracts to a significantly smaller size over a short period of time due to some random environmental event. In a true population bottleneck, the odds for survival of any member of the population are purely random, and are not improved by any particular inherent genetic advantage. The bottleneck can result in radical changes in allele frequencies, completely independent of selection.

Founder effect-occurring when a small group in a population splinters off from the original population and forms a new one. The random sample of alleles in the just formed new colony is expected to grossly misrepresent the original population in at least some respects

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natural selection

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stabilizing selection- against both extremes, mean grows.

directional selection- environmental change against one extreme, supporting another, mean shifts accordingly

Disruptive selection- selection against mean, extremes prosper.

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5. Charles Darwin and adaptation. Why did Darwin argue that there would be a “struggle for existence” among members of a species? How does natural selection help determine who the survivors in this struggle will be?

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Adaptation is the evolutionary process whereby a population becomes better suited to its habitat.[1][2] This process takes place over many generations,[3] and is one of the basic phenomena of biology.[4]

The term adaptation may also refer to a feature which is especially important for an organism's survival.[5] For example, the adaptation of horses' teeth to the grinding of grass, or their ability to run fast and escape predators. Such adaptations are produced in a variable population by the better suited forms reproducing more successfully, that is, by natural selection.

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Charles Lyell/Thomas Malthus and Darwin

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Lyell argued that the world had been shaped not by great catastrophes like floods but by the processes we see active today: wind, erosion, volcanoes, earthquakes etc. Lyell offered not just a new geology but a new philosophy of science.

Malthus had argued for a law-like relationship between population growth and food production in order to warn against what he feared was an immanent danger of overpopulation. Malthus was widely believed to have conclusively demonstrated that population would necessarily outstrip food production unless population growth were somehow checked.

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Homology vs Convergent Evolution

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Homology is where two (or more) species share the same basic structure, but it produces different functions. Example: a bat's wing and the hand of a human ... same basic bone structure, radically different function (flying vs. grasping).

Convergent evolution is where two (or more species) is basically the same function with very different basic structures. Example: a bat's wing and an insects wing. They have the same basic function to allow flight, and work in somewhat similar ways (by flapping), but they are completely different structures (insects don't have bones at all).


Homology is evidence that the basic structure was inherited from a common ancestor, and then *repurposed* for different functions.

Two very different structures that achieve a similar function is evidence that the two species came from very different ancestors that *converged* on the same function ... hence 'convergent evolution.'

Front 45

Biochemical evidence for evolution (DNA and/or protein sequencing)

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DNA and/or protein sequencing
Chlorophyll - same basic molecule in all photosynthetic organisms
Cytochrome C - respiratory enzyme common to all eukaryotic organisms
Enzymes - similar or identical enzymes are common to large groups of animals

1. trypsin - protein splitting enzyme - many animals from protozoans to mammals

2. amylase - starch-splitting enzyme found in everything from sponges to humans

Nucleic Acid comparisons (DNA fingerprinting) - the more closely related two organisms are, the more similar are their nucleic acids, e.g. identical twins