Ap Bio Chapter 3

Front 1

heredity

Back 1

the transmission of traits from one generation to next. Also known as inheritance.

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genetics

Back 2

the study of heredity and variation

Front 3

variation

Back 3

the genetic difference between siblings or members of same species.

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genes

Back 4

DNA segments, basic units of heredity that are transmitted from one generation to next.

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locus

Back 5

location of a gene on the chromosome.

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asexual reproduction

Back 6

single parent passes all genes to offspring. Usually just one single cell eukaryotes.

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sexual reproduction

Back 7

two individuals are contributing genes resulting in greater genetic variation.

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life cycle

Back 8

sequence of stages in its reproductive history through the course of its one generation.

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karyotypes

Back 9

the picture of its complete set of chromosomes arranged in pairs from the largest pair to the smallest.

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homologous chromosomes

Back 10

those that carry the genes that control the same traits;
similar in length an position of their centromere;
one is inherited from each parent.

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sex chromosomes

Back 11

the x and the y chromosomes that are not homologous;

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autosomes

Back 12

not sex chromosomes;

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gametes

Back 13

haploid sex cells - sperm and ovum

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fertilization

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the fusion of sperm and egg;

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meiosis

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the process by which in the course of gamete production the chromosome number is halved so that haploids are formed.

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three types of life cycles -

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1. humans plus most animals
meiosis occurs in gamete production. diploid zygote divides by mitosis to produce the organism.
2. fungi, protists and some algea - after gametes fuse to form the diploid zygote meiosis occurs occurs to produce haploid cells
these then divide by mitosis to give a haploid multicellular organisms
3. in plants and some algae- alternation of generations occur, including a haploid and diploid stage, the diploid is the sporophyte, and meiosis in the diploid phase creates haploid spores which divide mitotically to produce a gametophyt, the gametophyte produces haploid gametes through mitosis and the fertilization occurs producing a diploid zygote

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meiosis and mitosis

Back 17

both are preceded by replication of the DNA

Front 18

meiosis 1 and meiosis 2

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this replication of DNA is followed by two stages of cell division

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interphase

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each of the chromosomes replicate resulting in two sister chromatids attached at their centromeres, the centrosomes also replicate in this phase

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prophase 1

Back 20

chromosomes condense homologous (consisting of two sister chromatids)pair up, synapsis occurs-joining of two pairs of homologous chromosomes along their length, newly formed structures called tetrad has four chromatids, parts of the hologous chromosomes undergo crossing over at chiasmata (places at which homologous chromosomes overlap during synapsis, centrioles move to opposite poles, nuclear envelope disinegrates, spindle microtubules attach to the kinetochores, forming on the chromosomes that begin to move to the metaphase plate of the cell

Front 21

synapsis (prophase)

Back 21

joining of two pairs of homologous chromosomes at their lengh

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tetrad

Back 22

newly formed structure from synapsis has 4 chromatids.

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chiasmata

Back 23

where homologous chromosomes overlap during synapsis

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3 different things that lead to variation

Back 24

independant assortment, crossing over, random fertilization

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independant assortment

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in metaphase 1 chromosomes can pair up in any combination with any of the homologous pairs facing either pole

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crossing-over

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synapse, exchange of homologous parts of two

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random fertilization

Back 27

any sperm can hit egg

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trait

Back 28

a heritable feature of an organism that varies among individuals

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variation

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difference in a trait

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pure or true breeding

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all of offspring of of the same type, ex: when a pea plant is self pollinated

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hybridization

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the crossing or mating of two true breeding different varieties of an organism

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P generation (parental generation)

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true breeding parents in a hybridization

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F1 generation

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their offspring

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F2 generation

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their offspring if F1 generation is crossed

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4 major conclusions of mendal

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1. alternative versions of genes cause variation in inherited characteristics among offspring
2. for each character every organism inherits one allele from each parent
3. if two alleles are different the dominant allele will be fully expressed in offspring, a reccessive allele will have no noticable effect
4. the two alleles for each character separate during gamete production -mendels law of segregation-

Front 36

law of independant assortment

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each pair of alleles will segregate independantly during gamete formation

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homozygous

Back 37

same alleles

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heterozygous

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different alleles

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phenotype versus genotype

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appearance vs. genetic makeup

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testcross

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crossing of a recessive homozygote with an individual exibiting the dominant phenotype in order to find out if the organism is homozygous dominant or heterozygous dominant

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monohybrid cross

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cross involving the study of one character (flower collor)

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dihybrid cross

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two characteristics

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dihybrid genotype

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gene combination or genotype

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rule of multiplicationn

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when calculating the probability that two or more independant events will occur together in a specific combination, you multiply the probabilities of each of the two events

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rule of addition

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calculating the probability of an event that could happen any number of ways, you add the probabilities of the ways it could happeh

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incomplete dominance

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the F1 hybrids have an appearance that is between the two parents

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complete dominance

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heterozygote and homozygote for dominant allele are indistinguishable

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codominance

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two alleles are dominant and effect the phenotype in two different and equal ways, example is human blood type

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multiple alleles

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most genes exist in different forms, ex. is human blood type

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pleiotropy

Back 50

ability of a gene to effect many different traits in an organism

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epistasis

Back 51

ability of a gene at one location to alter the effects of a gene at a distant location

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polygenic inheritance

Back 52

two or more genes have an additive effect on a single character in the phenotype

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pedigree

Back 53

is male square female diagram, white no trait, black trait. through the patterns they reveal pedigrees can help determine the genome of individuals and can also help predict genome of future offspring

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recessively inherited dissorders

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alleles that cause genetic errors either code for a dysfunctional protein or no protein at all, both must be reccessive

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carriers

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heterozygotes with normal phenotype have the mutant allele

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cystic fibrosis

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mutation in an allele that codes for a certain cell membrane protein that functions in the transport of chlorine into an out of cell, breathing problems

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Tay-Sachs

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allele that codes for a dysfunctional enzyme that is unable to break down certain lipids in the brain

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cycle cell anemia

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caused by an allele that codes for a mutant hemoglobin molecule that forms long rods when the oxygen levels in the blood are low,

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huntingtons disease

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example of a late acting lethal allele

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chromosome theory of heredity

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early 1900s, stated genes have specific loci on chromosomes, it is chromosomes that segregate and assort independantly

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sex-linked gene

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one located on the sex chromosome, usually on the Y, fathers can only pass it on to daughters, women must be homogenous for it to take effect

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autosomes

Back 62

non sex linked genes

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linked genes

Back 63

located on same chromosome inherited together during cell division, red hair and freckles, do not do independent assortment but can have recombination by crossing over, farther apart genes are from each other the greater chance of recombination

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genetic recombination

Back 64

production of offspring with new combination of genes inherited from parents

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recombinance

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individuals who receive new combination of genes from parents

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parental types

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receive non-recombinant genes, their phenotype matches that of one of the parents

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genetic map

Back 67

ordered list of the genes and their loci along a particular chromosome using recombination data

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linkage map

Back 68

genetic map based on recombination frequencies and map units are used to express distances along the chromosome

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map units

Back 69

equal to a one percent recombination frequency

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sex linked disorders

Back 70

muscular distrophy, hemophilia, caused by absence or defection of a protein

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Barr body

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inactivated chromosome in women so that they have the same number of working genes as men

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non-disjunction

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members of a pair of homologous chromosomes do not separate properly during meiosis one or sister chromatids dont separate properly in meiosis two as a result one gamete receives two copies of the gene while other gamete receives none

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aneuploidy

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if the faulty gametes engage in fertilization the offspring will have an incorect number of chromosomes

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trisomic

Back 74

fertilized eggs that have received three copies of the chromosome in question

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monosomic

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fertilized egg receives just one copy of a chromosome

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polyploidy

Back 76

condition of having more than two complete sets of chromosomes somewhat common in plants

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deletion

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chromosome segment that has no centromere, broken off and lost during segregation, cell that receives partial chromosome will be missing that fragment

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duplication

Back 78

if the chromosome fragment that broke off causing the deletion above becomes attached to its sister chromatid, zygote will get a double dose of genes on that chromosome

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inversion

Back 79

a chromosome fragment breaking off and then reataching to its orginal position but backwards

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translocation

Back 80

chromosome fragment joins a non homologous chromosome, this moves a segment of one chromosome to a non homologous chromosome

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genetic disorders caused by chromosomal stuff

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down syndrome-aneuploidy condition of chromosome 21, trisomic for 21

-clinefelter syndrome-aneuploid condition in which a male posseses XXY

-turner syndrome- just one X chromosome, called monosomy

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x-ray crystallography

Back 82

process used to visualize molecules three dimensionally, refracting x ray images, DNA first visualized

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double helix

Back 83

twisted ladder with rigid rungs

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semi conservative

Back 84

at the end of its replication each of the daughter molecules has one old strand derived from the parent strand of DNA and one strand that is newly synthasized

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origins of replication

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sites at which the replication of DNA begins

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replication bubble

Back 86

initiation proteins bind to the origin of replication and separate the two strands

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DNA polymerase

Back 87

enzyme that catalyzes the elongation of new DNA at the replication fork

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anti parrallel

Back 88

strands of DNA run in the opposite direction

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leading strand

Back 89

DNA replication occurs continuously along this strand

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lagging strand

Back 90

DNA replication does not occur continually along this strand

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okazaki strand

Back 91

lagging strand synthesized in these separate pieces which are sealed together by DNA ligase to complete DNA strand

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primase

Back 92

enzyme responsible for initiating DNA replication, joins RNA nucleotides to create a primer which is required in order for a DNA polymerase to proceed

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DNA helicases

Back 93

enzymes that are responsible for unwinding the DNA helix as replication proceeds

Front 94

single strand binding proteins

Back 94

holds the strands apart for the duration of replication

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several different factors contributing to accuracy of DNA replication

Back 95

1. specificity of base pairing
2. mismatch repair - special repair enzymes fix incorrectly paired nucleotides
3. nucleotide excision repair - incorrectly placed nucleotides are excised by an enzyme called nuclease, and gap is filled with the correct nucleotides

Front 96

telomerase

Back 96

DNA polymerase can only add mucleotides to the 3' end of a molecule.- it would have no way to complete 5' end of molecule. so, linear chromosome of eukaryotes utilize this enzyme which catalyzes the ends of the molecules, called telomeres.

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one gene-one polypeptide hypothesis

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each gene codes for a polypeptide, which canb-or can constitute a part of - a protein

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transcription

Back 98

the synthesis of RNA using DNA as a template. takes place in nucleus of eukaryotic cells

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Messenger RNA or mRNA,

Back 99

type of RNA produced during transcription. carries genetic message of DNA to protein making machinery of the cell in cytoplasm.

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translation

Back 100

synthesis of polypeptides. takes place in the cytoplasm of eukaryotic cells at ribosomes

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pre-mRNA

Back 101

transcription results in this,
undergoes RNA editing and processing to yield the final mRNA that participates in translation

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triplet code

Back 102

in DNA the instructions for building a polypeptide chain are written as a series of three nucleotide groups

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template strand

Back 103

in transcription only one strand of the DNA is transcribed - this is the strand...

Front 104

codons

Back 104

complementary strand is mad eup of triplets called codons that are read or translated, in the 3' to 5' direction along the mRNA. Each codon specifies on of the 20 amino acids which are incorporated into a growing polypeptide strand

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redundant

Back 105

genetic coed is reduncant, more than one codon codes for each of the 20 amino acids.

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reading frame

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cotons are read based on a consistent reading frame - the groups of 3 must be read in the correct groupings in order for translation to be successful

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RNA polymerase

Back 107

enzume that separates the 2 DNA strands and connects teh RNA nucleotides as they base pai along the DNA template strand. (RNA polymerases can add only RNA nucleotides to teh 3' end of the strand, so RNA elongates in the 5' to 3' direction

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promotoer sequence

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DNA sequence at which RNA polymerase attaches

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terminator

Back 109

DNA sequence that signals the end of the transcripton

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transcripton unit

Back 110

the entire stretch of DNA that is transcribed into mRNA

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three main stages of transcription

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1. initiation
2. elongation
3. termination

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initiation - prokaryotes

Back 112

in prokaryotes a group of proteins plus RNA polymerase, bound to promoter region of a DNA sequence is collectively known as a transcription initiation comples.

Front 113

initiation - eukaryotes

Back 113

process is more complex, but it also involves the binding of RNA polymerase to a promoter sequence

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Elongation

Back 114

RNA polymerase moves along the DNA, continually added to the 3' end of the growing chain. as complex moves down the DNA strand, the double ehlix reforms with the new RNA molecule straggling away from the DNA template.

Front 115

termination

Back 115

occurs after RNA polymerase transcribes a terminator sequence in DNA, and the transcribed RNA sequence is the actual termination signal