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BIO 111 > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

Nucleic Acids

A

Large molecules composed of a chain of smaller nucleotide molecules

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2
Q

Nucleotide

A

Composed of one phosphate group (PO3), one 5-carbon, ringed sugar, and one of five nitrogenous base molecules

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3
Q

RNA

A
  • Ribose Sugar
  • Adenine, Uracil, Cytosine, and Guanine base molecules
  • 100-50000 nucleotides in nucleic acid strand
  • single stranded; linear
  • variety of functions related to protein synthesis
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4
Q

DNA

A
  • Deoxyribose sugar
  • Adenine, Thymine, Cytosine, and Guanine base molecules
  • Chromosomes have about 45 million nucleotides in nucleic acid strand
  • Double stranded helix; bases bonded by weak hydrogen bonds
  • Stores genetic information (genes) that direct RNA to perform protein synthesis
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5
Q

Complementary Base Pairs

A

Certain bases will form weak hydrogen bonds between them; no exchange of electrons; allow two long strands of DNA to stick together; the second strand is complementary to the first

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6
Q

Central Dogma

A

DNA replication
Protein Synthesis
- DNA –transcription–> mRNA –translation–> protein

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7
Q

DNA Replication

A

A process that allows two identical copies of DNA for the bacterial chromosome occurring prior to cell division:

  • Helicase unwinds and “unzips” the double stranded helix at the origin of replication (begins process)
  • Bacteria have one origin of replication; eukaryotic cells have many (several thousand)
  • Unwinds and unzips in both directions (5’ to 3’)
  • Complementary base pairing of new nucleotides to the original strands (adenine — thymine; cytosine – guanine)
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8
Q

Chromosome

A

Short, thick strand of DNA and protein; regulate cellular activity by controlling which genes are expressed to produce proteins

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9
Q

DNA Polymerase

A
  • Proof reads the new complementary nucleotide base pairs
  • Joins the new complementary base pairs together
  • This proceeds until two identical strands are made; strands will eventually separate
  • 500-1000 base pairs in a second
  • E. coli has 4,639,221 base pairs
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10
Q

Lead Strand

A

DNA replication occurs towards the replication fork; nucleotides are added continuously in the 3’ direction

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11
Q

Lagging Strand

A

DNA replication occurs away from the replicating fork; nucleotides are added in segments in the 5’ direction (Okazaki fragments)

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12
Q

Semiconservative Replication

A

Type of DNA replication in which half of the original strand of the DNA molecule is conserved in each new DNA molecule produced

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13
Q

Organization of the Chromosome

A

Circular; made of DNA and protein; divided into genes, each of which is a sequence of DNA nucleotides; Bacterial cells will:

  • code for the production of a single protein (coding region
  • regulate the expression of genes (regulatory region)
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14
Q

Promotor

A

An area where RNA polymerase will bind to a chromosome (always unzipped)

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15
Q

Operator

A

A gene can be turned off by placing a protein here

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16
Q

Triplets

A

How genes are divided; composed of a sequence of three nucleotides found within the same gene; if the gene codes for a protein, this will code for one specific amino acid found within the protein that will be produced; 64 possible combinations but only 20 different amino acids (more than one for each amino acid)

17
Q

Stop Triplets

A

Found at the end of the coding region, they stop the reading of a gene

18
Q

Protein Synthesis

A

The joining of amino acids to produce proteins; occurs in two distinct phases: transcription and translation

19
Q

Transcription

A

Steps used to convert a segment of DNA (template) into mRNA

20
Q

mRNA (messenger)

A

A sequence of codons that is a complementary copy of a single gene; carries the information from the DNA to the ribosome; must be present for translation to occur

21
Q

Phases of Transcription

A
  • Initiation: The enzyme RNA polymerase attaches to the promotor region of a gene
  • Elongation: The enzyme unzips the DNA molecule and moves along the template of DNA, synthesizing a single stranded mRNA strand one nucleotide at a time
  • Termination: The enzyme encounters a “stop signal” and terminates the construction of mRNA
  • A typical gene is composed of 1000 nucleotides and it takes about 30 seconds to make a copy
22
Q

Translation

A

The synthesis of an amino acid strand (protein) from codons found on mRNA

23
Q

Ribosome

A

Made of rRNA and protein; mRNA binds here; must be present for translation to occur

24
Q

tRNA (transfer)

A

Brings a specific amino acid to the mRNA and ribosome; must be present for translation to occur:

  • three nucleotides (anti-codon) which is complementary to the codon found on the mRNA
  • charged when a specific amino acid is attached to it
  • uncharged, it will not have specific amino acid attached, but will eventually find and attach to become charged
25
Q

Phases of Translation

A
  • Initiation: mRNA binds to the 30S portion of the ribosome
  • Elongation: A protein is constructed, one amino acid at a time
  • Termination: The ribosome reaches a “stop codon” which will terminate production of the protein, and the protein is released
26
Q

Stop Codons

A

Found at the end of a mRNA strand that signal the termination of protein synthesis; UAA, UAG, and UGA

27
Q

Erythromycin

A

An antibiotic that binds to the 50S subunit, inhibiting protein synthesis

28
Q

The Elongation Phase of Translation

A
  • P site: first tRNA will bind here, it is complementary to the first mRNA codon
  • A site: second tRNA will bind here, it is complementary to the second mRNA codon
  • the two charged tRNA will release their amino acid which form peptide bonds between them, forming a short polypeptide
  • the mRNA shifts over one codon and the process continues one amino acid at a time, until a stop codon is reached
29
Q

Environmental Effects on Anabolic Chemical Reactions

A

Bacteria live in environments that are changing rapidly; their energy supply or supply of essential nutrients may “dry up”; they must be able to control their biochemical pathways in order to conserve energy (90% of energy used goes to protein synthesis) and spare materials

30
Q

How Bacteria Conserve Energy and Spare Materials

A
  • Will utilize any and all molecules found within the environment instead of producing them themselves; genes that control the production of certain molecules will be turned off during periods of plenty: energy is conserved and can be used in cell division
  • When molecules dry up, the macromolecule must be produced by the machinery of the cell; genes must be able to turn on when needed: energy reserves are used up inside the cell and cell division occurs slowly
31
Q

End Product Repression

A

The end product of a series of chemical reactions will inhibit the expression of a gene and prevent further synthesis of all those enzymes necessary to produce the end product (turns genes on or off); e.g., production of the five enzymes responsible for the production of tryptophan

32
Q

Production of Tyrptophan

A
  • Five genes (one of each enzyme) are located side by side and controlled by the same promotor and operator region (operons); if RNA polymerase attaches to the promotor and no inhibitor exists, then all five genes will be expressed
  • Another gene is responsible for the production of an inactive inhibitor protein; it will not bind to the operator region unless this end product is very abundant
  • If so, then it will bind to the inhibitor protein, changing its shape, and allowing it to bind to the operator region; the synthesis of all the enzymes are inhibited; once the enzymes within the cell are used up, synthesis of this product will cease
33
Q

Feedback Inhibition

A

The end product will inhibit the function of one enzyme (of a series of enzymes) responsible for the synthesis of the end product

34
Q

Non-Competitive Inhibition

A

An inhibitor molecule binds to the allosteric site of an enzyme and permanently changes the shape of the enzyme, preventing the substrate from binding to the enzyme

35
Q

Competitive Inhibition

A

An inhibitor molecule binds to the active site of an enzyme and prevents the substrate from binding to the enzyme

BIO 111 (15 decks)

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