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Molecular Genetics
maddison and Juliens Q-cards
8
Biology
12th Grade
02/13/2008

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Term
Describe what happens in all the stages of Mitosis
Definition
Interphase - G1:rapid growth after mitosis

S phase: Dna synthesis

G2: growth befor division

Prophase: nuclear membrane disolves, centrioles move to opposite poles and spindle fibers attatch to the centromeres of replicated chromosomes

Metaphase: chromosomes line up at the center of the cell (equatorial plate)

Anaphase: spindle fibers contract and cromatids are pulled to either side of the cell

Telophase: nuclear membrane reforms, cell plate (in plant cell) forms down the middle, cleavage furrow  forms (in animal cells)  cytoplasm splits

Term

Explain the process of cloning

Definition
nucleus is removed from a mature cell. it is tricked into re-entering its embryonic state. This Nucleus is then placed into an enucleated cell and then it is planted into the surrogat mother
Term
What are the stages in meiosis and give a brief description of each. Where does meiosis occur
Definition

Meiosis I:occurs in the ovaries and the testies

Prophase I: nuclear membrane disolves, crossing over occurs, cetrioles move to poles, spindle fibers form

Metaphase I:homologous chromosomes line up at the eqatorial plate

Anaphase I: segregation occurs, one member of each homologous pair is sent to opposite ends of the pole

Telophase I: nuclear membrane begins to form, chromosomes in nucleus are NOT identical

Interphase II:no doubling of dna. this is just time between meiosis I and meiosis II

Prophase II: nuclear membrane dissolves and spindle fibers form

Metaphase II:chromosomes line up at equator and spindle fiber attatch to  centromere

Anaphase II:sister chromatids move to opposite poles as the attachment beteween the two chromatids breaks, nuclear membrane begins to form around the chromosomes

Telophase II: division of the cytoplasm 4 haploid daughter cells are produced all with unidentical DNA

 

Term
compare Mitosis and Meiosis
Definition

Mitosis: 1 division; 2 daughter cells, exact same dna, 2n(diploid), no synapsis, growth of an organism, asexual reproduction, replases old cells

Meiosis: 2 divisions; 4 daughter cells, Dna not the same, n (haploid), synapsis occurs to form tetrad, produces gametes

Term
If non disjunction occurs during anaphase I how many chromosomes will be in each of the four daughter cells. What about if non disjunction occurs in Anaphase II?
Definition

Anaphase I: n+1, n+1, n-1, n-1

Anaphase II: n+1, n-1, n, n

Term
Outline the steps in transcription
Definition

Initiation: RNA polymerase binds the sense strand to the dna which opens the helix.

Elongation: rna polymerase starts building single stranded mRNA. uracil is used instead of thymine

Termination: rna polymerase reaches end of gene and recognizes this because of a specific termination sequence (stop signal). mRNA detaches from the DNA strand and the DNA reforms

Term
Outline the steps in translation
Definition

Initiation: ribosome binds to nRNA strand. translation begins when the ribosom reaches the start codon

Elongation: transfer RNA is responsible for carrying the amino acids. methionine is carried to the p site. the second tRNA enters the A site and a peptide bond formss between methionine and the second amino acid. this process continues until it reachesn the stop codon

Termination: ribosome reaches stop codon. a release factor recognizes the stall form the ribosome and causes the subunit to detach the nRNA and the new polypeptide is released

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