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Mol / Cel Biology > Lecture 3 > Flashcards

Lecture 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the genetic code?

A

Genetic code is the set of DNA or RNA sequences that determine the amino acid sequences used in the synthesis of an organism’s proteins.
It is the biochemical basis of heredity.

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2
Q

How many codon combinations there is?

A

64 combinations. 4nt x 4nt x 4nt (nt= nucleotide)

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3
Q

The code is?

A

Non-overlapping, one triplet code codes for one amino acid.

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4
Q

Start and stop codons for RNA?

A

AUG and stops are UAA, UAG, UGA

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5
Q

What is genome?

A

The total genetic content.

Provides all of the information the organism requires to function.

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6
Q

What does eukaryotic genome contains?

A

A gene, the fundamental, physical and functional unit of heredity.

In molecular terms, a gene is chromosomal DNA sequence required for synthesis of a functional protein or RNA molecule.

Coding regions (exons), transcriptional-control regions and introns (non-coding regions).

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7
Q

A gene structure? (tough love)

A

At the 5’ end:
- promotor region (recognition of some proteins, which may start the transcriptional process).

Within the 5’ -region:
- TATA box, CpG island, locus control region.

5’ UTR (untranslated region)

3’ UTR

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8
Q

What is TATA box for?

A

Important for determining the position of start of the transcription.
Consists of 5-TATAAA-3’ sequence.

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9
Q

What are CpG islands for?

A

Sequence rich with C and G, usually found in ‘‘housekeeping’’ genes.

They bind some transcription factors and are targeted for DNA-methylation which leads to the repression of gene expression.

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10
Q

Give one example of CpG islands repression in gene expression.

A

If cytosines are bonded with methyl groups, the promotor region of the gene is blocked ->
Transcriptional factors cannot access DNA anymore ->
cannot initiate transcription.

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11
Q

What is locus control region for?

A

Ability to enhance the expression of linked genes, regulates more genes together.

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12
Q

5’ UTR (untranslated region) contains?

A
  • Initiator element (Inr)
  • Open reading frame (ORF)
  • Exon
  • Intron
  • Polyadenylation signals
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13
Q

Something about the initiator element?

A

Have a cytosine at -1 position and an adenine at the transcription start site +1.
Regulatory sequences to promote ribosome binding with mRNA

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14
Q

What is a open reading frame?

A

The sequence from start to the stop codon.
The first codon on the coding strand of DNA is ATG.
STOP codons are: TAG; TAA; TGA.

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15
Q

How many codon forms every region of DNA has?

A

Six possible reading frames, three in each direction.

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16
Q

What is exon? (Only eukaryotic cells)

A

Exon is a coding sequence of a eukaryotic gene’s DNA that uninterrupted transcribes into protein structures.

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17
Q

What is intron? (Only eukaryotic cells)

A

Noncoding DNA sequence of a eukaryotic gene’s that is not translated into a protein, BUT transcribed to the mRNA.

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18
Q

What are polyadenylation signals?

A

AAUAAA sequence -> serves as the 3’ -end cleavage.

Promotes downstream transcriptional termination.

19
Q

3’ UTR region contains?

A

Regulatory sequences to promote very rapid degradation of mRNA.
Regulate levels of translation.

20
Q

What is an enhancer?

A

Regulatory DNA sequences that binds specific proteins.

Enhances the transcription of an associated gene.

21
Q

What is a silencer?

A

Binder of repressor to regulate silencer sequences turns off transcription.

22
Q

More complex organisms (genomes) have decreased or increased density?

A

Decreased density. (Eukaryotes vs. prokaryotes)

23
Q

'’Genes and related sequences’’ consists of (2) regions that are? (GREEN!)

A
  • Coding and regulatory regions.

- Introns, promoters, pseudogenes

24
Q

'’Intergenic region’’ consists of (2) regions? (YELLOW)

A
  • Repetitious DNA

- Unique DNA

25
Q

Repetitious DNA consists of? (YELLOW)

A
  • Simple repetitives

- Transposones

26
Q

Simple repetitives consists of (3) satellites which are? (YELLOW)

A
  • Satellite
  • Minisatellite
  • Microsatellite
27
Q

Transposones consists of (4)? (YELLOW)

A
  • SINE
  • LINE
  • LTR
  • DNA
28
Q

Major protein coding genes in human genome?

A

Solitary genes - one copy in haploid genome.

Duplicated genes - genes with close but non-identical sequences

29
Q

The human alpha- and beta-coding region codes for? (Protein)

A

They cope for the same kind of proteins, but the proteins have some differences

30
Q

Pseudogenes?

A

Non-functional gene copy

31
Q

Tandemly repeated genes encodes for?

A

rRNA’s, tRNAs, snRNAs and histones

32
Q

Satellite DNAs are?

A

non-coding DNA sequences

33
Q

Minisatellite DNAs are?

A

Includes telomerases and sub-telomeric regions of all chromosomes

34
Q

Microsatellite DNAs are?

A

Disperses through all chromosomes

35
Q

Transposons (transposable elements) are?

A

Mobile DNA sequences. Can migrate to different regions of genome.

36
Q

Retrotransposons (SINE, LINE, LTR) are?

A

Copy and paste mechanism.

37
Q

DNA transposons are?

A

Mobile elements that transpose through a DNA

38
Q

Unique DNA sequences are?

A

Unclassified, non-coding DNA sequences.

39
Q

Functions of transposones?

A

Important for genome plasticity. Leads to deletions/duplications or inversions.

40
Q

Insertion into genes can disrupt gene function and cause diseases if?

A

Transposons interferes with gene coding sequences

41
Q

How are prokaryotic genes different than eukaryotic genes?

A

Higher gene density.
Simpler gene structure, doesn’t consist of introns.
Promoter region has two regulatory sequences.

42
Q

How is prokaryotic genome different than eukaryotic genome?

A

No simple repetitive DNA sequences.

Operons.

43
Q

What is operon?

A

Genes that are grouped together based on similar functions. Units are called operons.

Mol / Cel Biology (17 decks)

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