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MicroBiology > Chapter 4: Genes > Flashcards

Chapter 4: Genes Flashcards

1
Q

what is genetics?

A

the study of heredity

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2
Q

what is heredity?

A

passing on characteristics (traits) from parents to offspring so offspring resemble parents and eachother

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3
Q

list 4 microbial traits

A
  1. ) shape and structure (morphology)
  2. ) biochemical reactions (metabolism)
  3. ) movement and behavior
  4. ) interactions with other organisms (pathogenesis)
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4
Q

what is phenotype?

A

actual, expressed properties or characteristics (traits)

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5
Q

what is genotype?

A

organisms genetic makeup (total collection of genes)

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6
Q

what is genome?

A
  • total genetic makeup in cell (can mean genotype)
  • all the cells DNA
  • all viruses’ DNA or RNA
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7
Q

what is environment?

A

any factor affecting the expression of a phenotype other than genes

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8
Q

__________+_________—>___________-

A

genotype + environment–>phenotype

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9
Q

the functional unit of genetic information is the _____

A

gene

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10
Q

describe what genes are the 4 things they encode for

A

Segment of DNA in cells (or either RNA or DNA in viruses) which contained the coded information that determines:

  1. ) the sequence of mRNA which determines the primary structure of a given polypeptide (coding or structural genes)
  2. ) the sequence for rRNA (ribosomal RNA genes)
  3. ) the sequence for tRNA (transfer RNA)
  4. ) the sequence of regular RNA
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11
Q

are genes in cells single stranded DNA or double stranded

A

double stranded (ds) DNA

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12
Q

what is the flow of biological information

A

Genes (genotype)–> mRNA and other RNA–> polypeptide primary sequence–>proteins (enzymes)–> regulates cell chemistry–>determines cell/viral morphology and physiology (phenotype)
(slide 7)

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13
Q

DNA is a polymer of what?
RNA is a polymer of what?
what links these together?

A

DNA-deoxyribonucleotides
RNA-ribonucleotides
phosphodiester bonds

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14
Q

DNA and RNA differ in (2 things)

A

the nitrogenous bases they contain

the sugars they contain

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15
Q

describe DNA structure (6)

A

-polymer is deoxyribonucleotides
-bases are adenine, guanine, cytosine, and thymine
-sugar is deoxyribose
-adenine (purine) and thymine (pyrimidine) pair by 2 hydrogen bonds
-guanine (purine) and cytosine (pyrimidine) pair by 3 hydrogen bonds
-in all cells, DNA molecule is a double stranded helix
(slides 14-17; 17 is a video)

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16
Q

slide 13

A

information about DNA length

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17
Q

describe RNA structure (5)

A
  • polymer is ribonucleotides
  • sugar is ribose
  • bases are adenine, guanine, cytosine, and uracil
  • phosphodiester bonds
  • In cells, Most RNA molecules are single stranded; some double stranded or have double strand regions
18
Q

Three different types of RNA exist which may differ from each other in function, site of synthesis, and in structure. What are they?

A 
messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)
19
Q

describe viral genomes (8)

A
  • Either DNA or RNA in same virus particle, not both
  • DNA or RNA can be single stranded (ss) or double stranded (ds)
  • Viral nucleic acid had very little or no protein associated with it
  • Viral nucleic acid can be linear or circular
  • Viral genomes may consist of 1 piece of nucleic acid or several (ie, Influenza virus had 8 pieces ss RNA)
  • Most viral genomes have between about 20 and 100 genes (some larger exceptions)
  • Viral genomes consist of between 20,000 and 100,000 nucleotides
  • Viral genomes are packed within a protein coat called the capsid
20
Q

describe prokaryotic genomes (7)

A
  • Always composed of ds DNA
  • ds DNA has only a little protein associated with it
  • Bacterial chromosome is about 98% ds DNA and 2% protein
  • Most DNA is circular and supercoiled; some linear
  • Most have a single piece of DNA as their bacterial chromosome; but some have 2 or more
  • Prokaryotes have between about 2000 – 5000 genes
  • Prokaryote genomes are between 2 million and 5 million nucleotides
21
Q

what are plasmids? about how many genes?

A
  • Small pieces of open circular ds DNA in the cytoplasm

- Found in many prokaryotes; between 5 – 50 genes

22
Q

slides 23 and 24

A

pictures of super coiled DNA

23
Q

describe eukaryotic genomes (6)

A
  • Always composed of ds DNA
  • Mostly linear; some circular
  • DNA spread over many eukaryotic chromosomes
  • Most eukaryotes have several chromosomes
  • All members of same species have same number of chromosomes (called species number or chromosome number)
  • Eukaryotic chromosomes are structures for organizing a lot of DNA in a little volume
24
Q

each eukaryotic chromosome consists of (3 things)

A
  1. ) 34-35% ds DNA
  2. ) ~1% RNA
  3. ) 64-65% proteins (histones and non histones)
25
Q

Eukaryotic chromosomes can exist in several types of packing. Describe (2)

A

-During non dividing times (interphase), they are the most loosely packed (decondensed); at this time, the individual chromosomes exist but are not visible and they are referred to as chromatin
-During mitosis or meiosis, the chromosomes condense and become more tightly packed; they are also visible as individual chromosomes at this time
(slide 28)

26
Q

what are the 5 levels or eukaryotic chromosome structure?

A

1.) ds (naked) DNA- 2nm
2.) nucleosomes- 10nm (held together by histone proteins)
3.) solenoids- 30nm (held together by histone and non histone proteins)
4.) 300nm fibers- supercoils (held together by non histone proteins)
5.) higher levels- only occur during cell division
(slide 30 and 31)

27
Q

what is DNA replication? (2)

A

-Complex process involving numerous proteins which help ensure accuracy
-The 2 strands separate, each serving as a template for synthesis of a complementary strand
(slides 33 and 34; 34 is video)

28
Q

slides 35-39

A

35: weird information to make into card; look at
36: picture
37: video
38: more weird info to make into card
39: table

29
Q

name and describe the 5 materials required for DNA synthesis/replication

A

slides 40-42

30
Q

describe DNA replication

A

44-47 and in purple notebook

31
Q

describe replication machinery (2)

A
  • DNA polymerase catalyzes synthesis of complementary strand of DNA
  • DNA synthesis in 5’ to 3’ direction forming phosphodiester bonds
32
Q

replication machinery enzymes require what 3 things?

A
  1. ) a template – directs synthesis of complementary strand
  2. ) a primer – DNA or RNA strand
  3. ) dNTPs (dATP, DTTP, DCTP, dGTP) – deoxynucleotide triphosphates
33
Q

slide 51

A

E. Coli replication?

34
Q

describe DNA gyrase (2)

A
  • topoisomerase

- also introduces negative supercoiling to help compact bacterial chromosome

35
Q

describe primase

A

synthesizes short complementary strands of RNA (~10 nucleotides) to serve as primers needed by DNA polymerase

36
Q

DNA ligase forms a ________________ between 3’-_________ of the growing strand and the 5’-_________ of an Okazaki fragment

A

phosphodiester bond; hydroxyl;phosphate

slide 54-56

37
Q

describe proofreading (3)

A

-Carried out by DNA polymerase III
-Removal of mismatched base from 3’ end of growing strand by exonuclease activity of enzyme
-This activity is not 100% efficient
(57-58)

38
Q

slide 59

A

E Coli?

39
Q

Telomerase is an enzyme found in eukaryotes that can do what?

A

synthesize DNA using an RNA template and an internal RNA template thus solving the “end” replication problem

40
Q

describe the end replication problem and how this is solved in euks and bacteria

A

-shortening of chromosomes after each round of replication
-solved in eukaryotes by telomerase enzyme
-solved in bacteria by disguising the ends of the linear chromosome
(61-62)

41
Q

describe accuracy of DNA replication

A

last slide :)

MicroBiology (17 decks)

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