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180 Cards in this Set
- Front
- Back
Asexual Reproduction
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One parent gives to offspring that are IDENTICAL to the parent
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Who uses Asexual Reproduction?
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Prokaryote
single celled eukaryotes (yeast, euglenas) single celled protists multicellular (star fish plants) |
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What is the consequence of asexual reproduction?
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All offspring are genetic equals (not much variation)
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Sexual Reproduction
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Two parents, offspring are different from each other and parents
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The two phases of eukaryotic cell cycle
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Interphase
Mitosis |
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What are the 3 subphases of interphase?
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1) G1
2) S 3) G2 |
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G1 (Gap 1)
3 things |
1) before dna synthesis
2) increase in cell organelles 3) general growth |
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S (Synthesis)
3 things |
1) DNA replication occurs
2) Chromosomes replicate and remain joined to their replicated partner (sister chromatids) 3) More cell growth |
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G2 (Gap 2)
3 things |
1) After DNA synthesis
2) Increase in protein synthesis 3) General metabolic activity (making ATP) and growth |
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Mitosis (M) 4 subphases
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1) prophase
2) metaphase 3) anaphase 4) telephase |
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90 percent of the cells time is in what phase?
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Interphase
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Interphase prcedes what two processes?
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mitosis and meiosis
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Prophase
4 things |
1) DNA condenses (coils) becomes visiible in light microscope
2) Nuclear envelope and nucleolus disappear 3) spindle- begins to form (microtubules) --attaches to kinetochore, centrosome 4) sister chromatids (replicated chromosomes) move towards the equator of cell |
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This is what one end of a spindle joins to, its located at the centromere of each chromatid
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kinetochore
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The other end of a spindle joins to this microtubule organizing center?
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centrosome
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Metaphase "midway"
3 things |
1) Sister chromatids are at metaphase plate (equator)
2) Spindle is completed 3) nuclear envelope is completely gone |
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If spindle fibers at the equator are not attached to chromatids, what are they attached to?
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Other fibers originating at the opposite pole
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Anaphase
3 things |
1) sister chromatids seperate and become chromosomes and go to opposite poles
2) spindles shorten (attached to chromosomes) 3) spindles lengthen (attached to other fibers) causing the cell to elongate |
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When does telophase (cytoskinesis) begin?
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once all chromosomes are at spindle poles
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Telophase/cytokinesis
(4) things) |
1) DNA- uncoil
2) Nuclear envelopes and nucleoli reappear 3) spindle disappears 4) cytokinesis cell divides into two |
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Cytokinesis (cell divides into two) in animals
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"cleavage"
ring of microfilaments pinch cell in middle, and cytoplasm divides into two cells |
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Cytokinesis (cell divides into two) in plants
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"Cell plate formation"
Fusion of vesicles filled with cell wall materials at the equator forms two cells |
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Two types of proteins that are "doers" of the cell cycle
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1) kinases
2) growth factors |
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Kinases
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enzymes that add phosphates to other proteins
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Growth factors
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proteins that activate various genes telling the cell to grow and divide
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Two classes of "checkpoint" gene products (proteins) that regulate mitosis?
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1) proto-oncogenes
2) tumor suppressors |
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Which checkpoint class is like the gas in a car?
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proto-oncogenes
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Which checkpoint class is like the brakes in the car?
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tumor suppressors
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3 major characteristics of all malignant neoplasms (cancers)
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1) grow and divide abnormally
2) cytoplasm and plasma membrane become altered, cytoskeleton shrinks 3) weakened capacity to adhere |
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What kind of impact does cancer have on the developed world in terms of the cause of death?
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causes 15-20 percent of all death
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Why does a drug like taxol work to kill cancer cells?
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It keeps microtubules from diassembling and hampers mitosis
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How many new cases of breast cancer are diagnosed in the U.S. each year?
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200,000
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What kind of proteins are BRCA-1 and BRCA-2?
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Tumor suppressor
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Normall, BRCA proteins bind to receptors that then do what?
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Regulate the transcription of growth factor genes
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How is this process altered when there is a mutant BRCA protein?
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Growth factors are overproduced because BRCA cannot bind to the receptors. Cell division goes out of control, and tissue growth becomes disorganized which leads to cancer
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According to may sources including the American Society of Breast Surgeons, the risk of getting breast cancer if a woman inherits a mutant BRCA gene is what?
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80 percent
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What is the estimated risk of getting breast cancer for the average woman?
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12 percent
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Gamete
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a sex cell(sperm or egg)
meiosis of diploid cell |
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Somatic cell
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Any cell that is not a gamete
It is mitosis of a diploid cell |
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Homologous chromosomes
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two chromosomes that are nearly identical (one from mom one from dad), same location, different "versions"
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Autosomes
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22 autosomes means 22 pairs of homologous chromosomes
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Sex chromosomes
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xx-female
xy-male |
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Which pair is the sex dermining pair in chromosomes?
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23rd pair
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Diploid cells
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two sets of chromosomes (2n)
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Haploid cells
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A single set of chromosomes
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Meisos: chromosomes number is reduced by?
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one diploid cell gives rise to 4 haploid cells
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What cells use Meiosis?
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specialized diploid reproductive cells in testes and ovaries
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What is the purpose of Meiosis (2)?
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1) Keep the chromosomes # from doubling each generation
2) Produce variation "shuffle the alleles |
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Meiosis stages
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1) interphase (GI,2,G2)
2) Prophase 1 3) Metaphase 1 4) Anaphase 1 5) Telophase 1 and cytokinesis 6) prophase II - Telephase II makes 4 haploid cells |
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Is interphase the same in mitosis and meiosis?
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yes
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What is different in prophase I than prophase of mitosis?
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1) chromatids align as tetrads
4 chromatids= replicated homologs 2) synapsis = crossing over occurs 3) hybrid chromosomes = result of crossing over |
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What is different in metaphase I than metaphase of mitosis?
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1) tetrads line up at metaphase plate
2) tetrads are attached to spindle fibers |
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Anaphase I
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homologs separate from each other
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Telophase I and cytokinesis
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1) spindle disappears
2) nuclear envelopes and nucleoli- reappear (some species) 3) DNA- may uncoil (some species) 4) Cytokinesis results in 2 cells (sister chromatids still joined) |
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Prophase II-Telophase II
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Same of mitosis, sister chromatid separate and produce four cells
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Is there interphase between meiosis I and meisos II?
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NO
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What separates in meiosis one?
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homologs seperate (2 cells form)
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What separates in meiosis two?
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sister chromatids seperate (4 cells form) HAPLOID
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Independent Orientation
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Orientation of homologs at metaphase I (Meiosis 1) plate
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According to Independent Orientation how many total number combinations in a diploid cell? formula?
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2 raised to n (number of pairs of chromosomes-combindations)
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How many total combinations would there be in humans? According to indepedent orientation?
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2 raised to 23
8 million |
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Random fertilization
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Fusion of the haploid nuclei of two gametes. This is where chromosome number is restored.
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Formula for random fertilization
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(2^n) (2^n)
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According to random fertilization how many combination's in a human?
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64 trillion combinations
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What leads to genetic variability (meiosis)?
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1) indepedent orientation
2) random fertilization 3) crossing over during synapsis of PROPHASE 1- random occurs approximately 1 to 2 times per homolog pair |
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Principle of segregation
Gregor Mendel |
Diploid cells have pairs of genes on pairs of homologous chromosomes.
The two genes of each pair are segregated-seperated from each other during meiosis so they end up in different gametes |
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Genes
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unit of information about specific traits
ex: pea color |
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Humans have about how many genes spread out among their 23 chromosomes?
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22,000 genes
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How many copies of every gene are in each somatic cell?
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2 copies
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Alleles
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alternate versions of a gene
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Example of allele?
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yellow or green
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Pure breeding or homozygote
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two identical alleles for a trait
ex: AA, aa |
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Hybrid or heterozygote
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two different alleles
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Dominant allele
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Allele that is expressed in a heterozygote
Aa= yellow |
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Recessive allele
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Allele that is masked in a heterozygote
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Genotype
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allelic composition of a gene
Aa, AA, aa |
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Phenotype
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expression of a trait
yellow or green |
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Tester
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homozygous recessive for all genes being examined
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Homozygote x Homozygote
genotypes of offspring? phenotypes of offsprint? |
genotypes: all the same
phenotypes: all the same |
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Monohybrid x Monohybrid
genotypic ratio? phenotypic ratio? |
genotypic ratio: 1:2:1
phenotypic ratio: 3:1 |
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Monohybrid x tester
genotypic ratio: phenotypic ratio: |
genotypic ratio: 1:1
phenotypic ratio: 1:1 |
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Mendels principle of independent assortment
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As meiosis ends, genes on pairs of homologous chromosomes have been sorted out for distribution into one gamete or another, independently of gene pairs of other chromosomes.
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Dihybrid x dihybrid
phenotypic ratio? |
9:3:3:1
9: both dominant 3: one dom, one recessive 3: one recess, one dominant 1: both recessive |
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Dihybrid x tester
phenotypic ratio? |
1:1:1:1
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3 things Mendel did not observe
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1) multiple alleles
2) codominance 3) incomplete inheritance |
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Multiple alleles
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3 or more alleles for one gene in a population
A1, A2, A3 example: red blood cells Ia (rbcs make a antigen on surface), Ib(rbcs make b antigen on surface), i (rbcs make no antigen) |
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Codominance
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They are both expressed in a heterozygote
ex:Ia and Ib |
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Incomplete Dominance
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One allele of a pair is not fully dominant over the other in a heterozygote, so an "intermediate" phenotype is observed
ex: A (red) and a (white) Aa (pink) Phenotypic ratio and genotypic ratio are the same |
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Rule of Multiplication (Product Rule)
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The probability of a compound event is the product of separate probabilities
(.5x.5x.5....) |
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Rare Autosomal Dominant Disorders
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Need one dominant allele to have the disease. (A/a=disease, A/A death rarely seen a/a normal)
Affected individuals usually have one affected parents Doesnt skip generations |
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Examples of Rare Autosomal Dominant Disorders (2)
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1) achondroplasia- dwarfism
2) huntington's disease--neurological |
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Rare Autosomal Recessive Disorders
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Needs two recessive alleles to have the disease (A/A normal, A/a normal carrier, a/a has disease)
Affected individuals usually have unaffected parents Skips generations Inbreeding increases frequency in a population |
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What increases Rare Autosomal Recessive Disorders in a population?
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inbreeding
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Examples of Rare Autsomal Recessive Disorders (3)
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1) cystic fibrosis
2) tay sachs disease 3) sickle cell disease |
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Cystic fibrosis
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-1 in 20 carriers
-most common genetic disease in Caucasians -it is thick mucus in lungs and respiratory tract, chronic lung infections, malnutrition because of missing pancreatic enzymes, infertility in males, salty babies |
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Tay Sachs Disease
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-neurological
-jewish child dead by 3 |
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Sickle Cell Disease
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-1 in 12 carriers
- defect with hemoglobin -most common genetic disease associated with individuals of African descent |
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Examples of some common autosomal single gene Traits (4)
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1) feckles, no freckles
2) widows peak, straight hairline 3) free earlobes, attached earlobes 4) left thumb, right thumb these are not rare, and they do not affect survival or reproduction |
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Rare X-linked recessive disorders
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mutated gene is located on the x chromosome
only one recessive allele is needed in males to have disease females would need two copies |
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Rare X-linked recessive disorders: usually have affected or unaffected parents?
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unaffected parents
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What increases Rare X linked recessive disorders?
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inbreeding in population
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Examples of rare x-linked recessive disorders (3)
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1) red-green colorblindness
2) hemophilia- bleeding disorder 3) muscular dystrophies- muscular degenerative diseases |
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Anueuploidy
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Abnormal number of chromosomes in humans
(2n + 1) 47 chromsomes |
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What causes Anueploidy?
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errors in meiosis; nondisjunction in meiosis I and meisis II
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Non disjunction in meiosis I
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Homologs dont seperate; all aneuploid (n+1) (n+1) (n-1) (n-1)
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Non disjunction in meiosis II
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Sister chromatids dont separate in one of the two cells; 1/2 aneupoloid
(n) (n) (n+1) (n-1) |
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Aneuploidy in autosomes
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monosomy
trisomy |
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Monosomy
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Losing one autosome, not compatible with life (human)
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Trisomy
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Gain one autosome
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Trisomy 13,18,21
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down syndrome, only ones that make it through development to birth
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What increases the risk of Aneuploidy in autsomes?
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Woman ages because her eggs are arrested in prophase I, non-disjunction becomes more common
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Aneuploidy in sex chromosomes
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gain or loss of sex chromosome
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Examples of aneuploidy in sex chromosomes (4)
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XXY
XYY XO XXX |
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XXY
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Trisomy; Kleninfelters syndrome, feminized male, tall and thin, immature breasts, sterile
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XYY
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"Criminal phenotype"
normal fertile males taller more acne lower IQ |
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XO
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"Turners syndrome"
monosomy of the x webbed neck short sterile (female) |
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XXX
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normal fertile females
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Fred Griffith
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investigated the nature of genetic material mouse experiment with s & r stains of streptococcous
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What was the consensus at the time on genetic material?
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That eukaryote chromsomes carry genetic material and it consists of DNA and proteins
Genetic material was either DNA or proteins |
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Oswald Avery, Colin MacLeod, Maclyn McCarty
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Test nature of genetic materials, DNA-inheritable, similar experiment with mice
Use DNase and protease to determine |
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Alfred Hershey and Martha Chase
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Stuided T2 Bacteriophage which was comprised of DNA (inside) and protein (coat)
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What were the two batches of phages with radioactivity labeled as
DNA? Protein? |
DNA: Phosphorous
Protein: Sulfur |
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What was done to the bacteria infected (2) batches?
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they were infected, agitated, spun
spun to seperate the phage proteins (light) and bacteria cells (heavy) |
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What were the protein results labeled as? What were the DNA results labeled as?
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Protein: solution
DNA: Pellets |
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What conclusion did Alfred Hersey and Martha Chase make?
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DNA was inhertiable material
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Edwin Chargaff
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Purines (A,G)
Pyramidines (T,C) ration of bases C:G= 1:1 A:T= 1:1 |
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Purines
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A, G
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Pyramidines
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T,C
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Rosalind Franklin and Maurce Wilkins
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Used x-ray defraction as their main tool
Their data suggested the diameter of DNA, repeating units |
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James Watson and Francis Crick
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Helix diameter (2nm)
Determined there were two strands Determined base pairings: A and T, G and C |
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The two strands of the double helix are?
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antiparallel
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DNA is a _____ helix of two long _____ strands
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double, antiparallel
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Polynucleotides
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many nucleotides
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Nucleotides
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sugar base and phosphate
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Bases bond with each other with ______ bonds. how?
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hydrogen bonds
G and C = 3 bonds A and T = 2 bonds |
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What does it mean when it says DNA is semiconservative?
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Each new strand is comprised of an old strand and a new strand
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What makes it possible for DNA to be semiconservative?
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1) first stage of mitosis (interphase-s phase)
2) each strand of a double helix is a template for a new strand. it unwinds and the old is a template 3) half of every double stranded DNA (old) AND half is new |
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Enzyme that breaks hydrogen bonds between bases to unwind DNA into single strands
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Helicase
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Inserts new bases into the new strand
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DNA polymerase
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Transcription
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DNA to mRNA
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Translation
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mRNA to protein
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How many nucleotides are for each amino acids?
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3 (Triplet sequence)
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One strand of the double helix is "rewritten" in the code of mRNA
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Transcription
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Template
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single strand of DNA being used in transcription
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Complementary strand
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mRNA synthesized
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mRNA is decoded into language of proteins? what help this process?
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Translation
tRNA (interpretor) |
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How many bases in mRNA is for one codon?
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every triplet bases (three bases)
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How many amino acids for a codon?
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one
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How many codons can code for one amino acids?
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more than one
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Transcription in eukaryotes occurs where?
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nucleus
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Adds RNA nucleotides to the growing RNA at the 3' END
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RNA polymerase
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Importance sequences in DNA
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1) Promotor
2) coding region 3) terminator |
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Coding region (transcription)
2 sequences |
Exons (Sequences that will be expressed)
Introns (sequences that will not be expressed) |
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Promotor and Terminator
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gene start
end of transcription |
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Post transcription processing of mRNA
(3) |
1) addition of 5' cap
2) addition of 3' poly A tail 3) exons get spliced together (introns are lost) |
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Where is the transcript shuttled from?
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nucleus to the cytoplasmathrough nuclear pores
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What are the 5 players of translation?
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1) mRNA
2) ribosome 3) tRNAs 4) amino acids 5) enzymes that attach amino acids to tRNAs |
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Location of translation?
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at a ribosome in cytoplasm either free or attached to RER
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What is the tRNA "interpreter" functions
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1) carries the approporate amino acid to the ribosome
2) recognize the appropriate codon in mRNA |
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What is the structure of tRNA?
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Anticondon-triplet sequence complementary to the codon
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Ribosomes function in translation
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1) serves as a meeting place for the tRNAs and the mRNA
2) catalyze a reaction. They form peptide bonds between amino acids |
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Structure Ribosomes
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1) large and small subunits made of rRNA and proteins
2) P site and A site: groves that hold tRNAs involved in the process |
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The grooves that hold tRNAS involved in the process
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P site and A site
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Start codon
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AUG
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Stop codon
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UAA, UAG, UGA,
they do not code for amino acids |
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Initiation (phase one of translation)
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1) small subunit of ribosome binds mRNA
2) tRNA binds start codon 3) large subunit of ribosome clamps down |
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Elongation (phase two of translation)
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1) codon recognition- tRNA carrying appropriate amino acid recognizes the codon and sits in the groove of ribosome
2) peptide bond formation- forms between the amino acids sitting in the grooves 3) translocation- ribosome moves over on codon |
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Translocation
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ribosome moves over on codon
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Peptide bond formation
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forms between the amino acids sitting in the grooves
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Codon recognition
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tRNA carrying appropriate amino acid recognizes the codon and sits in the groove of ribosome
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Termination (phase three of translation)
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stop codon, polypeptide is freed
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4 ways mutations arise
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1) spontanesously in dna repliaction
2) ionizing radiation (xrays) 3) nonionizing radiation (uv light) 4) chemicals |
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Ionizing radiation causes what type of mutations?
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double stranded breaks in DNA
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Nonionizing radiation causes what type of mutations?
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UV light
frameshift mutations |
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Chemicals cause what type of mutations?
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base substitutions
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Some stem cells seem to have more abilities, or possibilities, than other stem cells termed...
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potency of the stem cell
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Stem cell that can only form one differentiated cell type
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unipotent
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A stem cell can form multiple different cells and tissue types
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multipotent
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A stem cell can form most or all of the 220 differentiated cell types in the adult body
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pluripotent
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A stem cell can form not only all adult body cell types but also specialized tissues needed for development of the embryo, such as the placenta
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totipotent
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