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12 Cards in this Set

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know what experiments were done and what the experiments were trying to demonstrate or discover
griffith-how certain types of bacteria produce pneumonia; rough=harmless; heat killed smooth=harmless; heat killed smooth+rough=harmful; smooth=harmful;heat killed bacteria could transform into a killer bacteria (transformation) something was transferred

avery-added enzymes to destroy lipids, carbs, proteins, and rna; transformation still occurred and only dna was left

hershey+chase-used viruses to demonstrate that what the virus injects is dna and thats what takes over the cell; proteins- sulfur; dna-phosphorus; dna controls the cell

chargaff-analyzed organisms and found that a=t and g=c

wilkins-invented a meathod of determining molecular structure by using x-ray diffraction to see how the atoms are arranges with a crystal

franklin-purified/crystalized dna and took x-ray diffraction pictures of the molecule; provided verification that the molecules was a helix and measurments of where the nucleotides were in relation to one another

watson+crick-dna molecule was a double helix with a=t and g=c
what is chargaff's rule?

why is it true?
adenine=thymine
guanine=cytosine

hydrogen bonds can form between certain base pairs (base pairing)so a=t and g=c
what are dna and rna nucleotides composed of?
rna-ribose, phosphate group, adenine, uracil, cytosine, guanine

dna-deoxyribose, phosphate group, adenine, cytosine, guanine, thymine
what is occurring during replication, transcription , and translation?
replication-copying process by which a cell duplicates its dna

transcription-process in which part of the nucleotide sequence of dna is copied into a complementary sequence of rna

translation-decoding of a mrna message into a polypeptide chain
how does rna differ from dna?

how many kinds of rna are there and what does each of them do?
rna-ribose, uracil, single-stranded, 3 forms

dna-deoxyribose, thymine, double-stranded, 1 form

3 forms
mrna-carries copies of instructions for the assembly of amino acids into proteins from dna to the rest of the cell

trna-transfers amino acids to ribosomes during protein synthesis

rrna-makes up the major part of ribosomes
what are the steps of translation?
1.edited mrna leaves the nucleus and finds a ribosome

2. 2 triplet codons line up inside the ribosome

3. a trna arrives carrying its amino acid and base pairs with the 1st triplet codon

4. a 2nd trna arrives and base pairs with the 2nd triplet codon

5. amino acids join witht the help of enzymes in the ribosome

6. the first trna falls off

7. the ribosome moves over

8.another trna moves in and repeats cycle until a string of amino acids has been assembled into a protein

9. hist the stop codon, protein falls off, mrna comes off ribosome in cytoplas or rough er
what does it mean when the genetic code is described as a redundant?
multiple ways to code for the same protein, repeats
explain the different types of mutations and why some are more serious than others
1.gene mutations-changes in a single gene

a. point mutation-changes in one or a few nucleotides

aa.substitutions-one base is changed to another

bb.insertions-a base is inserted into a dna sequence

cc.deletions-a base is removed from a dna sequence

b.frameshift mutations-shifts the frame by adding or deleting a nucleotide

2.chromosomal mutations-changes in a chromosome

a.deletions-loss of all or part of a chromosome

b.duplication-prouce extra copies of parts of a chromosome

c.inversions-reverse the direction of parts of chromosomes

d.translocation-part of a chromosome breaks off and attaches to another

e.polyploidy-has extra sets of chromosomes

f.triploid-3n

g.tetraploid-4n

some have little or no effect on the expression of genes or function
how does the lac operon function?
genes are turned off by repressors and on by the presence of lactose. when latose isnt present the repressor binds to the operator region, preventing rna polymerase from beginning transcription.lactose causes the repressor to be released from the operator region to begin transcription.
how do eukaryotes control their genes?
individually and have regulatory sequences that are much more complex than the lac operon. some enhance transcription by opening up tightly packed chromatin. others help attract rna polymerase and some block access to genes
describe the process by which the first copy of mrna is modified before it is translated and expain why this must occur
introns and exons are copied from the dna molecule. then the introns are cut out while they are still int the nucleus. the exons are then spliced back together. this makes it possible for a single gene to produce several different form of rna
explain what would happen if a mutation occurred in a gene for a repressor protein.
couldnt turn on or off the gene so it would result in too much or too little protein