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Biology > ch 9 > Flashcards

ch 9 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Gene Expression

A

Protein Synthesis

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2
Q

list the differences between DNA and RNA

A

DNA

  • double-stranded
  • uses thymine
  • has deoxyribose sugar ring
  • located in the nucleus in Eukaryotes
  • Contains information for making proteins
  • longer
  • 1 kind

RNA

  • single stranded
  • uses uracil
  • has ribose sugar ring
  • Moves from the nucleus to cytoplasm
  • Uses information to make proteins
  • shorter
  • at least 3 kinds
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3
Q

Transcription

A

nucleotides in DNA info “transcribed” into nucleotides in mRNA, tRNA, and rRNA

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4
Q

describe Enzyme RNA polymerase

A

Enzyme RNA polymerase

  1. Binds to DNA at promoter (beginning) sequence site.
  2. Splits double helix by breaking hydrogen bonds between nitrogen bases
  3. Transcribes nucleotide sequences to mRNA substituting uracil for thymine.
  4. Stops at terminator sequence site (DNA helix hydrogen bonds reform)

In Eukaryotes, enzymes cut introns out of RNA and reconnect exons before mRNA leaves nucleus

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5
Q

Translation

A

nucleotides in mRNA are “translated” into amino acids in protein

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6
Q

Codon

A

sequence of 3 nucleotides; codes for 1 Amino acid

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7
Q

Codons nearly universal

A

almost all organisms use the same codons for the same amino acids…which means we all came from a common ancestor.

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8
Q

Translation steps:

A
  1. mMRA binds to smaller ribosomal unit – its start codon is at “P” site
  2. tRNA carrying its specific amino acid binds to start codon at the “P” site with its complementary anti-codon end
  3. Large ribosomal unit attaches to form fully functional ribosome
  4. next tRNA carrying its specific amino acid binds to next codon at “A” with its complementary anti-codon end
  5. a peptide bond is formed between the new and older amino acids
  6. tRNA at “P” detaches, leaving amino acid attached to amino acid attached to tRNA at “A” site
  7. mRNA and the attached tRNA at “A” and its attached amino acids move to “P” (shifts 1 codon length over - codon that was at “A” site now at “P” - a new empty one is at “A”)
  8. next tRNA carrying its specific amino acid binds to next codon at “A”….etc.
  9. Process continues until stop codon reached - when everything is released
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9
Q

Operon

A

cluster genes on DNA that code for proteins with related functions plus regulatory regions: promoter, operator

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10
Q

Promoter

A

region “upstream” of genes is the landing site for RNA polymerase

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11
Q

Operator

A

region of between promoter area of operon and coding genes.

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12
Q

where does RNA polymerase bind?

A

RNA polymerase binds to promoter region.

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13
Q

what happens if a repressor molecule is bound to the operator?

A

If repressor molecule is bound to operator the transcription of coding genes to mRNA is blocked and cannot proceed.

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14
Q

how is a repressor released?

A

Repressor released when inducer molecule binds to it.

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15
Q

Gene regulation in Eukaryotes:

A

Genes with related functions are scattered among chromosomes.

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16
Q

why can’t RNA polymerase bind to transcription site?

give an example

A

RNA polymerase cannot bind to transcription site without the presence of a cluster of proteins called transcription factors. Other proteins called the initiation complex bind to an enhancer site, which can be distant from gene transcription area and then it touches the transcription factors and RNA polymerase is released to transcribe.

Example: Estrogen hormone (controls secondary sex characteristics)

  1. Estrogen passes into cell and binds to receptor protein on nuclear envelope creating hormone-receptor complex
  2. Receptor complex binds to acceptor protein
  3. Acceptor protein binds to enhancer site which turns on transcription process for proteins related to secondary sex characteristics
17
Q

Point mutations

A

change just one or a couple nucleotides

18
Q

Substitution

A

one nucleotide substituted for another.

19
Q

Insertions or deletions

A

one or more nucleotides added or deleted affecting all codons in sequence after point (frame shift)

20
Q

Mutagens

A

environmental agents that may induce mutations

21
Q

Carcinogen

A

cancer causing mutagen

22
Q

Cancer

A

unrestricted cell growth.

23
Q

Tumor

A

cancer cell growth area

24
Q

Benign

A

does not invade surrounding tissues

25
Q

Malignant

A

invades other tissues (metastasis)

26
Q

Oncogene

A

gene that when mutated can cause cell to become cancerous

Biology (16 decks)

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