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55 Cards in this Set
- Front
- Back
Gene |
Segment of DNA that codes for a specific trait |
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Allele |
The specific version of the gene on a chromosome -diploid organisms have 2 alleles for each gene; one for each member of a homologous pair |
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Locus |
Physical location of a gene on a chromosome |
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Dominant |
If present, the allele shows itself (CAPITAL) |
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Recessive |
Can be masked by a dominant allele (lowercase) |
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Homozygous |
Having 2 identical alleles for trait |
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Heterozygous |
Having 2 different alleles for trait |
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Genotype |
Specific alleles for an organism |
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Phenotype |
The observable traits of an organism (Not only appearance) |
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Gregor Mendol |
-Studied plants in 1800's -Used phenotypes or parents & offspring to determine genotypes -Hypothesized that each plant had 2 units of info for each trait -Tested this with pea plants -Punnett Squares |
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How to do Genetic Problems |
1. Parent Genotypes 2. Gametes produced by each parent 3. Offspring genotypes from crossing parents 4. Offspring phenotypes |
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Genetic Disorders |
1. Chromosomal Abnormalities (errors in meiosis) 2. Spontaneous Mutation in genes to make new dangerous allele 3. Specific Inherited alleles passed through generations |
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Autosomal Recessive Alleles |
-Must have 2 affected alleles to get disorder -Heterozygotes are carriers --> have one allele but not disorder |
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Autosomal Dominant Alleles |
-Only need one allele to get disorder -affected individuals can be homozygous or heterozygous ex: achondroplasia - type of dwarfism Huntingtons Disorder - fatal degenerative disorder of the nervous system |
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Incomplete Dominance |
-No allele is completely dominant -Heterozygotes show blending ex: Snapdragon flowers ---> red and white alleles can create a pink flower |
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Co-Dominance |
-When different alleles are present, phenotypes of both are expressed in their pure form (NO blending) -Blood typing in humans -Different alleles code for different types of surface molecules on blood cells |
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Pleiotrophy |
One gene affects more than one phenotypic characteristic |
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Epistasis |
-Expression of trait can be masked by alleles from second gene ex: coat color in Labrador Retrievers; one gene for color, one gene to deposit pigments |
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Polygenic Inheritance |
-Phenotype determined by additive effects of 2 or more genes -can lead to continuous variation |
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Genotype/Environmental Interactions |
-Can influence expressed phenotype -ex; coat color in Siamese cats and himalayan rabbits, flower color in hydrangeas |
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DNA Structure |
-Structure discovered by Watson and Crick based on x-ray pictures and data from American Chemist Chargaff -Two nucleic acid strands join together when bases form hydrogen bonds -Result is double helix -Base pairs ---> A to T, C to G |
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DNA Replication |
-Two strands are separated -Using base pair rules, DNA polymerase uses free nucleotides to make new companion strand for each parent strand -DNA ligase connects new fragments together -Parent strand and new strand re-form double helix -Special enzymes check and repair -Two new double helices, both identical to original -two sister chromatids -each double helix is one old and one new strand |
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What is DNA used for |
-Some DNA contains instructions for protein synthesis -Different genes code for different proteins -Letters of DNA code determine the order of amino acids in the protein |
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From DNA to RNA |
Transcription - DNA code is transcribed to messenger RNA and sent to cytoplasm Translation - Code from mRNA is used to make protein |
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Transcription |
-Happens in nucleus -mRNA made by RNA polymerase -uses DNA as template -uses base pairing code -RNA splicing ---> mRNA strand is 'edited' and sent to cytoplasm -Used as instructions for making protein |
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Translation |
Synthesis of protein using mRNA as instructions -Takes place in cytoplasm (on ribosomes made of protein and ribosomal RNA) -Each set of 3 nucleotides codes for 1 amino acid -One codon signals start, 3 codon signal stop -Some amino acids are coded for by more than one triplet -Requires carriers (transfer RNA) -Amino acids added one at a time, according to codons |
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Silent Mutation |
Changing 3rd nucleotide may not change amino acid due to redundancy in triplet code |
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Missense Mutation |
Changes one amino acid (usually from change in single nucleotide) |
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Nonsense Mutation |
Gets 'stop' codon instead of amino acid, and translation stops too soon |
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Frameshift Mutation |
A deletion or insertion of nucleotides can change every amino acid that follows |
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Mutations and Protein Synthesis |
-Changes in DNA sequence may lead to changes in amino acid sequence -Changes in amino acids will change protein structure -Can make proteins non-functional or just different |
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What Causes Mutations? |
Spontaneous - errors in replication or recombination Mutagens - environmental agents -U.V. radiation -Ionizing radiation -carcinogens PROGERIA - error in DNA replication prior to meiosis |
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How are Genes Controlled? |
-All cells have the same instructions, but most are specialized in structure and function -During development, cells become differentiated (uses only genes for that role) -Before differentiation, cells can become any type (stem cells) (embryonic stem cells are from embryos) (Somatic stem cells are from bone marrow, umbilical cord, etc.) |
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Gene Expression |
How genetic information is revealed in an organisms phenotype -In female mammals, on X chromosome is inactivated early in development -Transcription is prevented by -chromosome packing -methylation -Transcription also controlled by proteins that bind to DNA and either promote of inhibit transcription |
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Control of Gene Expression |
Post transcription regulation - mRNA can be degraded or translation can be locked -After translation ---> some proteins require activation before functioning, others can be broken down when no longer needed |
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Biotechnology |
Use of biological agents for advancements in agriculture, medicine, industry |
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Genetic Engineering |
Manipulation of DNA for practical purposes |
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Recombinant DNA |
When DNA from two or more species is combined |
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Restriction Enzymes |
-Occur naturally in bacteria, and cut up foreign DNA that gets into cells -Cuts DNA into fragments at specific locations -Allows 'pasting' together of fragments |
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Polymerase Chain Reaction |
To increase amount of DNA in small sample -Heating and cooling cycle creates copies -Uses heat-resistance taq DNA polymerase |
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Cloning |
Generally refers to a genetic copy -Making copies of DNA fragments (gene cloning) -Making genetic copy of an organism for reproductive purposes (reproductive cloning) -Making genetic copy of an organism (embryonic cloning) for research purposes, including biomedical (therapeutic cloning) |
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Animal Cloning |
-Nuclear transplantation -donor egg with nucleus -adult somatic cell with own DNA -cells shocked to fuse and stimulate division -Embryo can be transplanted to surrogate -reproductive cloning -Blastocyst is source of embryonic stem cells -therapeutic cloning |
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Cloning Genes |
-Making copies of genes using bacteria -Plasmid ---> extra circular piece of DNA found in bacteria -Source DNA and bacteria plasmid cut with restriction enzymes -Recombinant plasmid taken up by bacteria -bacteria will copy DNA when it divides -Copies of genes can be used for research |
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Reproductive Cloning |
-Has been accomplished in sheep, horses, cattle, mice, cats, dogs, goats, pigs, deer, and more -Applications -food animals, companion animals -endangered species
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Therapeutic Cloning |
Goal is to obtain embryonic stem cells that are a genetic match to patient -combine donor egg with cell from patient -Can use healthy cells to replace patients damaged cells (could potentially create a clone of someone else by using another persons embryo) |
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Genetically Modified Organisms |
An organism that contains DNA from another species (a recombinant organism) -Can be single celled or multicellular -Can be used to manufacture useful gene products or for food |
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Engineered Plants |
-Use engineered bacteria to "infect" plant and insert plasmid with desired gene into plant DNA -Resistance to pesticides, insect damage, disease -Tolerance of drought, freezing, salinity -Increased nutritonial value Very difficult to contain living organisms |
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Engineered Animals |
Food animals -disease resistance, higher production or better quality -Research animals to study human genes -Using animals to produce human proteins in milk |
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Gene Therapy |
-Many disorders caused by mutated alleles -Gene therapy -insert "good" allele to do the work of a bad allele -genes delivered to body in viruses or lipids -can't guarantee where genes will insert in genome |
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DNA profiling |
-DNA from blood, saliva, urine, hair, teeth, bone, tissue -Criminal investigations ---> easier to eliminate suspects than prove guilty -Genetic Relationships - offspring share half DNA with parents and 1/4 with siblings |
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What are the ways that people test for genetic disorders in their children? |
-Prenatal Diagnosis -obtain cells through amniocentesis |
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DNA Ligase |
Type of enzyme that is used when replicating DNA -joins the parents strand and new strand together |
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DNA polymerase |
Enzymes that create DNA molecules by assembling nucleotides |
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What are proteins made from? |
They're made from amino acids, joined together in chains |
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Exon |
Portion of DNA sequence that is not removed from pre-mRNA and is expressed in the protien |