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Flashcards in Chapter 2 Deck (131):
1

gene

series of DNA nucleotides that generally codes for the production of a single polypeptide or mRNA, tRNA, or rRNA

2

eukaryotes

have more than one copy of one gene

3

prokaryotes

have one copy of each gene

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genome

entire DNA sequence of an organism

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Central Dogma

DNA is transcribed to RNA which is translated to AA forming a protein

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DNA

polymer of nucleotides

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Purines

adenine and guanine -- two ring structures

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pyrimidines

cytosine and thymine -- single ring structures

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phosphodiester bonds

how nucleotides are bound to each other -- btwn the 3rd carbon of one deoxyribose and the phosphate backbond of a single strand of DNA

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5'-3' directionality

3' carbon attached to an -OH group and the 5' carbon is attached to a phosphate group

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anti parallel, double stranded

two DNA strands lie side by side in opposite 3'->5' directions, bound together by H bonds btwn nitrogeneous bases to form a structure

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base pairing

this hydrogen bonding is commonly referred to as ___

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length of DNA measured in

bp

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complementary strands

purine-pyrimidine pairs adenine and thymine and guanine and cytosine

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double helix

when complementary strands bind together

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DNA replication is semi conservatice

new double strand created, contains one strand from the originial DNA and one newly synthesized strand

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bidirectional process

two replisomes proceed in opposite directions along the chromosome making replication a _____ process

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DNA polymerase

enzyme that builds the new DNA strand, only add nucleotides to an exisiting strand

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primer

primase creates an RNA ____ approximately 10 ribonucleotides long to initate the strand

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lagging strand

made up of Okazaki fragments

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DNA ligase

ties Okazaki fragments together

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semidiscontinuous

since the lagging strand replication is fragmented

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leading strand

continuous new strand

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replication steps

helicase unzips , rna polymerase builds a primer, dna polymerase assembles the leading and lagging strands, primers are removed, okazaki fragments are joined

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telomeres

repeated 6 nucleotide units that protect chromosomes from being eroded through repeated rounds of replication

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RNA

has a hydroxyl group attached, single stranded, contains pyrimidine uracil, not confined to the nucleus

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mRNA

delivers DNA coded for AA to the cyotosol where the proteins are manufactured

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rRNA

combines with proteins to form ribosomes, synthesized in the nucleolus

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tRNA

transfer RNA, collects AA in the cytosol and transfers them to the ribosomes for incorporation into a protein

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transcription

RNA is manufactured from a DNA template

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intiatition

beginning of transcription, a group of proteins called iniation factors finds a promter on the DNA strand, and assembles a transciption iniation complex which includes RNA polymerase

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RNA polymerase

prokaryotes have one, eukaryotes have three

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promoter

a sequences of DNA nucleotides that designates a beginning point for transcription

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elongation

RNA polymerase transcibes only one strand of the DNA nucleotide sequence into a complementary RNA nucleotide sequence

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termination

requires special termination sequence and special proteins to dissociate RNA polymerase from DNA

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activators and repressors

bing DNA close to the promoter and either activate or repress the activity of RNA polymerase; often allosterically regulated by small molecules such as cAMP

37

operon

genetic unit consisting of the operator, promoter, and genes that contribute to a single prokaryotic mRNA

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primary transcript

addition of nucleotides; deletion of nucleotides; modification of nitrogenous bases

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5' cap

5' end is capped in a process using ATP; serves as an attachment site in protein synthesis and as a protection against degradation of exonucleases

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poly A

3' end is poladenylated with a ___ to protect against exonucleases

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introns and exons

primary transctipt is cleaved into introns and exons; introns stay in nucleus, exons exit nucleus to be translated

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snRNPs

recogonize nucleotides sequences at the ends of the introns

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spliceosome

several snRNPs+ proteins; introns cut out and exons are put together -- makes single mRNA

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denatured

when heated, put in high concentration salt solution or high pH solution, h bonds are disrupted and the two strands of the double helix are separated

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nucleic acid hybridization

DNA-DNA, DNA-RNA, RNA-RNA ; enable scientists to identify nucleotide sequences by binding a known sequence with an unknown sequence

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restriction enzymes

cut nucleic acid only at certain nucleotide sequences along the chain

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palindromic sequence

restriction site will be a ______ _____ four to six nucleotides long

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recombinant DNA

artifically recombined DNA, DNA fragments cleaved by the same endonucleaes can be joined together regardless of the origin of the DNA

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vector

what to use to insert DNA into a bacteria

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plasmid

what recombinant DNA could be placed into

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clone

large quantity of DNA containing the vector with the recombinant DNA fragment

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library

clones can be saved separately producing a clone _____

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screened

Libraries can be ___ for the appropriate clones, that have the appropriate resistances

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probe

radioactively labeled complementary sequence of the desired DNA fragment

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complementary DNA

mRNA is produced by the DNA is reverse transcribed using reserve transciptase

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PCR

double strand DNA amplified placed in a mixture with many copies of two DNA primers, mixture is heated and cooled; heat resistant polyermase is added, amplifies the comp strands which double amount of DNA, exponential increase of DNA

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anneal

hybridize; to their complementary ends of the DNA strands

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southern blotting

DNA to be identified is cleaved into restriction fragments; fragments move according to size by gel electrophoresis, large frags move more slowly, gel is made alkaline to denature DNA, membrane used to blot the gel that transfers the single strand DNA onto the membrane, probe with nucleotide sequence complementary to the target fragment is added to the membrane, add probe made from DNA or RNA; visualize with radiographic film

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northern blot

identifies RNA fragments v

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western blot

detect a protein with antibodies

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RFLP

identified individual as opposed to identifying specific genes

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genetic code

translates the DNA nucleotides sequence into an AA sequence that ultimately form into a protein

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degenerative

more than one series of 3 nucleotides may code for any AA

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unambiguous

single series of 3 nucleotides will code for one AA

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almost univeresal

nearely every living organism uses the same code

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codon

3 consecutive nucleotides on a strand of mRNA

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stop codons

UAA, UGA and UAG

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start codon

AUG

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anticodon

tRNA contains a set of nucleotides that is complementary to the codon

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ribosome

rRNA with protein, provides site for translation to take place

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small and large subunit

made from rRNA and many separate proteins, assembled in nucleolus, exported to the cytoplasm

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nucleolus

complex structure of ribomsomes requires this

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P site

tRNA with 5'-CAU-3' anticodon sequesters the AA methionine and settles in at the

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iniation complex

large subunit to join and form the

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iniation

tRNA and large subunit coming together

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elognation

tRNA with its AA attaches to A site at the expense of two GTP

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translocation

ribosome shifts 3 nucleotides along the mRNA toward the 3'end , the first tRNA moves toward E site where it can exit the ribosome

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termination

translation ends when a stop codon is reached. release factors bing to the A site allowing a water moleculte to add to the of the polypeptide chain, polypeptide is freed from the tRNA and the ribosome, ribosome breaks up its subunits to be used again

80

post translational modification

sugar, lipids or phosphate groups may be added to AA ,

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translation location

may happen in the cytosol or the ribosome may attach itself to rough ER and inject proteins into the ER lumen,

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mutation

alteration in the genome that is not genetic recombination

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gene mutation

alteration in the sequence of DNA molecules in a single gene

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chromosomal mutation

when structure of chromosome is changed

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mutagens

mutations arising from chemical agents

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point mutation

mutation changes a single base pait

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base pair substitution mutation

one base pair is replaced by another

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missense mutation

base pair mutation that occurs in the AA coding sequence of a protein

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frameshift mutation

when deletions or insertions occur in multiples other than three

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nonsense mutation

base pair substitution or an insertion or deletion that creates a stop codon

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chromosomal deletion

when a portion of the chromosome breaks off, or when a protion of the chromosome is lost during homologus recombination and/or crossing over events

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duplications

when a DNA fragment breaks free of one chromosome and incorporates into a homologous chromosome

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translocation

segment of DNA is inserted into another chromosome

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inversion

orientation of DNA is reversed on a chromsome

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transpons/transposable elements

excise themselves from a chromosome and reinsert themselves at another location; can cotain one gene, several genes or just a control element; how somatic cell can alter its genetic makeup without meiosis

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forward mutation or backward mutation

change organism back to original -- wildtype or make it further away from wildtype

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cancer

uncontrolled growth of cells

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oncogenes

genes that cause cancer

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carcinogens

mutagens that can cause cancer

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nucleosome

eight histones wrapped in DNA

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chromatin

entire DNA/ protein complex

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histones

DNA that are not in use are wrapped tightly around globular poteins

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somatic cells

46 double stranded DNA molecules

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chromosome

chromatin associated with each one of these molecules

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homologous

each chromose possess a partner that codes for the same traits as itself--gene might be different, both eye color one is blue eyes other is brown eyes

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diploid

any cell that cotains homologous pairs

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haploid

any cell that does not contain homologues

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interphase

G1, S and G2

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G1

cell just split, cell grows in size, RNA sythensis and protein synthesis are very active, usually longest stage

110

S phase

cell devote energery to replicating DNA, chromosome exactly duplicated, each chromsome is made of two identical sister chromatids

111

G0

nongrowing state, allows for difference in lenth of the cell cycle, mature neurons and muscle cells remain in G0 permamently

112

G2

cell prepares to divide, cellular oganelles continue to duplicate, G2 checkpoint checks for mitosis promoting factor

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mitosis

nuclear division without genetic change

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prophase

codensation of chromatin into chromosomes, centrioles move to poosite ends of the cell, spindle appartus begins to form consisting of aster

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metaphase

chromosoms align along the equator of the cell

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anaphase

sister chromatids split at their attaching centromeres

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cytokinesis

actual separationo of the cellular cytoplasm due to constriction of microfilaments about the center of cell may start at the end of ana phase

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telephase

nuclear membrane reforms followed by the reformation of the nucleolus

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meiosis

double nuclear divison which produce 4 haploid gametes/germ cells

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spermatogonium and oogonium

human cells that undergo meiois

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primary oocyte

arrested at this stage in females until puberty; undergoes first divison before ovulation to become secondary oocyte

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2nd oocyte and sperms

stimulates anaphase II in the oocye

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prophase I

homologous chromsomes lines up along side each other; exchange DNA nucleotides in a process called crossing over, genetic recombination-- 4 chromatids -- tetrads

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linked

genes located on a chromsome are more likely to cross over together

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metaphase I

homoloues remain atached, move to metaphase plate

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anaphase 1

separates homologues from their partners

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telpehase 1

nucelear membrane may or may not reform, cytokinesis may occur

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2nd spermatocyes and oocytes

if cytokinesis occurs

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polar body

from 2nd ooctye much smaller and degenerates

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meiosis 1

reduction division

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meiosis II

same is mitosis, final product 4 sperm cells, single oovum

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nondisjuction

during anaphase I or 2 centromere of chromosome does not split