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What is genetics

Study of function and transfer of genes

1

Importance of genetics

Understand cell function
Evolution of species
Advancement in agriculture
Understand diseases
Info on antibiotic resistance

2

What is genome?

ALL genetic info in cell
Contain chromosomes

3

How many chromosomes E.coli have?
How many genes?
How long is stretched out?

1 chromosome
4288 genes
Stretch 1mm if unwound

4

How many chromosomes do humans have?
Stretches??

46 chromosome
6 feet

5

What are chromosomes?

Contain genes

6

What are genes?

DNA segments

7

What are three types of genes?

Structural: code for protein
Regulatory: control gene expression
Genes that code for RNA

*structural most important

8

What are genetic code

Set of rules that determine how nucleotides sequence is converted into a protein

9

What is genotype?

Genetic make up
Represents potential characteristics
Ex. Serratia marcescens COULD turn red

10

Phenotype

Expression of genotypes
Actual observable characteristics

Ex. Serratia marcescens is red

11

What does DNA stand for

Deoxyribo Nucleic Acid

12

What are the component of Nucleic acid?

Nucleotides

13

What are the three nucleotides component?

5 carbon sugar
Phosphate
Nitrogenous base

14

What are the nitrogenous bases?

Adenine
Thymine
Cytosine
Guanine

15

What is complementary base pairing

Certain nucleotides bases pair together
A-T
G-C

16

What kind of bonds are between bases?

Hydrogen bonds

17

Each DNA molecule has

2 strands of nucleotides

18

Strained in DNA molecule are

Antiparallel 5' --> 3' and 3' --> 5'

19

Carbon of dexoxyribose are numbered

1' through 5'

20

5' end _______ add nucleotides(P)

Cannot

21

3' end _______ add nucleotides (OH)

Can

22

Flow of genetic information

DNA --------------> mRNA --> protein
^(Transcription). ^translation

24

DNA --------------> mRNA --> protein
^(Transcription). ^translation

Is called

Central dogma

25

what is genotype?

genetic make up
represent only potential charactersistics
ex. Serratia macescen COULD turn red

26

what are the steps of DNA replication?

1. double helix is seperated by helicase
2. replication fork forms at origin of replication
3. leading strand is synthesized continously as DNA polymerase add new nucleotides (5' to 3')
4. Lagging strand uses RNA primer to lay down short pieces of RNA
5. On lagging strand, DNA polymerase removed RNA primer and replaces it with DNA
6. On lagging strand DNA ligase joins fragments of DNA
7. DNA polymerase proofreads to ensure proper base pairing occurs

27

how is the lagging strand formed?

synthesized in pieces because there is no free 3' end

28

helicase

enzyme that unwinds double helix

29

template

original strand of DNA

30

where 2 strands are seperated and new nucleotides are added

replication fork

31

enzymes that add new nucleotides and proof reads

DNA polymerase

32

Small pieces of RNA where DNA polymerase can attach

RNA primer

33

enzyme that joins fragment of DNA (glue) on lagging strand

DNA ligase

34

Pieces of RNA fromed on teh lagging stand

OKAZAKI fragment

35

transcription

process of making mRNA from a DNA template

36

what is the end result of transcription?

mRNA

37

what does mRNA do:

carries infromation transcribed from DNA
*contains codons*

38

what does tRNA do?

carries amino acids
contains anticodons which pair with codons on mRNA

39

what does RNA polymerase?

Enzyme that make new strand of mRNA

40

what is the promotor?

Site on DNA template where RNA binds

41

what is the terminator?

site on DNA template that end transcription

42

what are the steps in transcription?

1. RNA polymerase binds to promotor site on the DNA template
2. RNA polmymerase synthesizes a complementary base strand of DNA template working in a 5' to 3' direction
3. transcription continues until a terminator is reached
4. RNA polymerase and new mRNA are released from DNA

43

what is translation?

process of protein synthesis

44

What is the end product of translation?

protien(enzyme)

45

how are ribosomes involved in translation?

site of translation attaches to mRNA
contains two sub units
30s and 50s
contians 3 tRNA binding sites

46

tRNA binding sites are?

A
P
E

47

What tRNA A site?

acceptor; hold tRNA carries the next amino acid

48

what is tRNA P site?

peptide; holds tRNA with growing peptide chain

49

what is tRNA E site?

exit

50

what are the steps in translation

intitiation
elogation
termination

51

what are the steps in initiation?

1. start condon, AUG, signals mRNA to bind to sm. subunits of ribosomes
2. initate tRNA ( with amino acid met.) attaches its anticodon (UAC) to mRNA in P site of ribosome
3. Large and small subunits of ribosome join

52

what are the steps in elongation?

1. mRNA is threaded through ribosome
2. 2nd tRNA with amino acid binds it anticodon with mRNA's codon A site of ribosome
3. peptide bond form between amino acid
4. polypeptide chain is transfered to tRNA in A site and 1st t RNA moves to the E site and is released
5. tRNA with growing peptide chain moves A to P

53

what are the steps to termination?

1. elongation. continues until a stop codon is reached at A site
2. Ribosome split apart polypeptide chain
*protien fold and becomes funtional*

54

what is a codon?

set of 3 nucleotides based mRNA that encodes for specific amino acid
64 possible codons and 20 amino acids
61 are sense codons
3 are nonsense codons

55

what are sense codons?

amino acids

56

what are nonsense codons?

UAG, UAA , and UGA

57

what is the regulation of gene expression?

most metabolic reaction are catalyzed by enzymes(protein)
cells only produce enzymes when they are needed and only perform needed chemical reaction
cell control activity by feedback inhibition
the process to make enzyme are controled by genetics; transcription and translation
genes that code fro enzymes that are needed most of the time say on all the time
genes that code for enzymes that are only need at certain times are regulated

58

what is feedback inhibiton?

inhibition of enzymes when reaction is unnecessary

59

what is the repression of genes?

process that turns off transcription
caused by over production of end product from metabolism
repressors block RNA polymerase at promotor

60

induction

the relief of repression for a gene or set of genes under negative control repressor

61

what is operon

system of gene regulation includes genes,promotor or operon

62

what is a promotor

where RNA polymerase starts transcription

63

what is operator?

start/stops transcription of lac gene

64

E. coli with lac gene

E. coli contains an inducibe systems for lactose metabolism

65

lac operon's job is to regulate what/

the lac. gene and there for regulate transcroption and translation

66

lac operon under normal conditions is

turned off when glucose is present

67

when lactose is present lac operon must

broken down by beta-galactosidase

68

what does beta-galactosidase do"

splits lactose--> glucosa and galactose

69

what does glucose and galactose do/

are used by E. coli in metabolism to make ATP

70

when the lac operon is on in E. coli in medium with lactose

1. lactose is transported into cell and converted to allolactose (inducer)
2. allolacotose binds to repressor (turn off) which turns on genes for RNA polymerase to transcibe mRNA
3. mRNA is translated and beta-galacosidase is produced

71

E. coli in medium without lactose operons is off

1. repressor active is bound to operator
2. mRNA is Not transcribed
3. Translatino do NOT occur
4. beta-galactosidase is NOT produced

72

what are mutation?

changes in base sequence of DNA
are permenant and passed to next generation
can help with environmental changes(natural selection)
ex. antibiotic resistance

73

what are base substitution?

single base in released with another base

74

missense mutation?

base substitution results amino acid substitution

75

nonsense mutation?

base substituition codes for nonsense codon

76

what is frameshift mutation?

one or more bases are deleted or inserted

77

what are mutagens?

substance that cause mutaion

78

what are the different types of mutagens?

chemicals -- nitrate and nitrite --household cleaners
radiation-- UV light and X-ray-- causes pyridine dimer (thymine) to form

79

what is genetic transfer?

exchange of genes between 2 DNA molecule to form new combination of genes

80

what are genetic cross over?

2 chromosome break apart and rejoin
results ; 2 original chromosomes have combination of each other

81

what is cross over important?

genetic recombination contributes to a population's genetic diversity
genes for resistance to drug and metabolic poison develop
new nutrional and metabolic capacities develop
increase virulence

82

what are plasmids?

circular pieces of DNA
replicated seperately from chromosomal DNA
can enhance pathogenicity

83

what are the three genetic transfer?

1. transfromation
2. conjugation
3. translation

84

what is transformation?

process of genetic transfer when a cell lyse and "naked' DNA is transfered to another bacteria

85

how does transforation work?

donor DNA combine with recipeint DNA form a new recombinant (if closely related)
occur in Bacilus and Streptococcus, and Staphylococcus

86

What is plasmid F factor?

used in conjugation
carres gene for sex pillus

87

what is plasmid R factor?

plasmid that transfered antibiotic resistance
transfer multiple resistance to antibiotic (tetracycline, chloramphenicol, stretomycin, sulfonamide, and penicillin)
synthesize factor such as toxin, enzymes adhesion
can transfer resistance to heavy metal

88

what is conjuagation in bacteria?

process of genetic transfer that involves sexual mating using a plasmid
require cell to cell contact
must be oppiosate mating type

89

what are the components involved in conjugation?

sex pilus: connection
Donor: has plasmid
F+
Recipeient: no plasmid
F-

90

what are the steps in conjuation?

1. sex pilus grows out F+ and attahes to F- cell
2. copy of F+ is transfered to recipient F0
result is F+ + F- = F+ + F+

91

what is the transduction?

process of genetic transfer in which DNA is passed from one bacterium to another by a bacteriphage

92

what are the steps in transduction?

1. bacteriphage attaches to a bacterium and injects its DNA
2. bacteriophage breaks down bacterium's DNA
3. bacteriphage replicates self and part of original bacterium's DNA is packed in new bacteriophage
4. bacteriophage lyse bacteria and infect other bacteria
5. new bacteriphages land a new bacteria and DNA of the two bacteria and combined

93

what are transpons?

segments of DNA that move from 1 region to antoher
"jumping genes"

94

what are the advantages of transpons?

creation of genetic diversity
change in traits such as pigmentation and morphology
replacement of damaged DNA

95

what are the disadvantages of transpons?

can lead to mutation
can cause cell dysfunction