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IB Bio HL > D1.2 Protein Synthesis > Flashcards

D1.2 Protein Synthesis Flashcards

1
Q

Definition

mRNA

A

messanger RN
made as a strand that is complementary to template strand of DNA, it therefore has opposite bases (including uracil)

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2
Q

tRNA

A

transfer RNA
carries amino acids to the ribosomes where they are bonded together to form polypeptide chains

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2
Q

Where does transcription happen in euk. and prok.?

A

eukaryotes = inside nucleus
prokaryotes = cytoplasm

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2
Q

rRNA

A

ribosomal RNA
found in ribosomes and codes mRNA into amino acids

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2
Q

Transcription outlined

A
  1. Helicase breaks H bonds in region of DNA => seperates bases
  2. RNA polymerase moves template strands
  3. RNA polymerase matches complimentary RNA nucleotides (C & G , A & U)
  4. RNA nucleotides bind to form pre mRNA
  5. DNA behing RNA polymerase rejoins into double helix
  6. when RNA reaches stop codon = chain is terminated = pre mRNA detaches
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2
Q

sense and antisense strand

A

sense= other strand

antisense (created in 5 to 3, BUT starts at 3 to 5 on the DNA strand it is coding on)= strand where mRNA is built

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2
Q

Stages of transcription

A
  1. Initiation= RNA polymerase binds to DNA at start of gene = seperates two DNA sztrands by breaking H bonds
  2. Elongation stage = RNA polymerase build mRNA on one DNA strand
  3. Termination stage = terminator sequence in DNA is reached = mRNA released
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3
Q

mRNA facts

A

when a polypeptide is required = triplet code converted to mRNA

  • it is recyced when no longer needed (broken down by nucleases)
  • single stranded
  • contains ribose sugar
  • contains uracil
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4
Q

Definition

Translation

A

after transcription, it is the process by which mRNA combines with ribosomes where proteins are built

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5
Q

Translation outlined

A
  1. mRNA attaches to ribosomes of methionine (AUG)
  2. tRNA with complementary anticodon attaches to mRNA
  3. tRNA is attached to amino acid
  4. ribosome moves along mRNA bringing in 2 tRNA at one time
  5. enzyme & ATP used to join amino acid with peptide bond
  6. first tRNA released = collects other AA = repeated until stop codon
  7. many ribosomes can travel along mRNA at same times = polysome
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6
Q

tRNA facts

A
  • small
  • single stranded
  • clover shaped
  • each tRNA can carry different AA
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7
Q

stability of protein synthesis main molecules

A

mRNA<tRNA<DNA

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7
Q

Triplet

A

3 nucleotide bases in DNA

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7
Q

anticodon

A

3 bases at opposite end of tRNA that complementarily bind to codon on mRNA

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7
Q

Codon

A

3 nucleotide bases in RNA/protein

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7
Q

central dogma of molecular biology

A

theory that explains how genetic information flows from DNA to RNA to produce a biologically functional product

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8
Q

How many times does each base exist in one unit of codons and triplets

A

only once

genetic code is non overlapping= each base is only in one codon/triplet

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8
Q

genetic code facts

A
  • sequence of nucelotides
  • triplet code (found by francis crick)
  • non overlapping
  • degenerate => most AA have more than one triplet code
  • universal= same base triplet code for same AA in all living organisms
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9
Q

point mutation

A

Can occur during DNA replication or transcription and involves a single nucleotide base being altered, inserted, or deleted in a DNA or RNA sequence

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10
Q

frameshift mutation

A

addition or deletion of a base that causes a shift in the reading frame

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11
Q

Sickle Cell Anemia

A
  • blood cells are in sickle shape instead of biconcave disk
  • causes heart stroke/attack, bone malformation, pneumonia
  • due to single base substitution of A to T
  • 6th triplet changes from GAG (GLU) to GTG (VAL)
  • prim & second structure of Beta subunit is altered
  • quaternary structure of haemoglobin changes
  • fibres are deformed
  1. long fibres poke into cell membrane = distorts shape
  2. ability to carry oxygen decreases
  3. block blood vessels
  4. puts strain on liver as it removes cells
  5. bone marrow has to continuously produce more
12
Q

Immediate effects of Sickle cell anemia

A
  1. long fibres poke into cell membrane = distorts shape
  2. ability to carry oxygen decreases
  3. block blood vessels
  4. puts strain on liver as it removes cells
  5. bone marrow has to continuously produce more
13
Q

Controlling transcription and translation

Transcription

A
  • limiting amount of mRNA produced from particular gene
  • post transcriptional events = regulate translation of mRNA
13
Q

Controlling transcription and translation

Directionality

A

Transcription= RNA polymerase builds mRNA 5 to 3

Translation= mRNA moves through ribosomes in 5 to 3 & only fits when orientated correctly

14
# Controlling transcription and translation Initiation of transcription at promoter stages
* RNA can only bind at promoter regions * transcription factors bind to promoter regions = allows RNA polymerase to bind * without TF = gene cannot be transcribed
15
# Controlling transcription and translation Non coding sequence
* 98% of human genome is non coding Made up of * regulators of gene expression * Introns = in eukaryotes; removed after transcription * telomers = found at ends of chromosomes * genes for tRNA and rRNA
16
Modifications and splicing
based on fact that mRNA needs to be modified before translating * pre mRNA contains two regions = exons and introns * mRNA contains only one region = exons Introns are removed by spliceosomes (large protein i n nucleus) Exons are joined together
17
Exons and introns
exon= protein coding region introns = non protein coding region
18
Alternative splicing
gene is spliced in multiple ways by combining different exons => creates different versions of proteins => Increased protein diversity from the same DNA
19
Binding sites within protein production
P site= initiator tRNA binds there A site = where incoming tRNA binds which is added to growing chain E site = tRNA moves here after transferring AA to growing chain and exits ribosome
20
Steps of ribosomes making proteins
* Initiation: 5' of mRNA binds to small ribosomal subunit * anticodon of intiator tRNA (carrying MET) binds to codon of mRNA * large ribosomal unit joins to assemble
20
how proteins gain fucntionality
* formed polypeptide packaged into vesicle by RER * moves to golgi apparatus => post-transformational modification
21
Proteasome
total of all proteins made and used by the body
21
How Insulin is made
* 4 sections= A chain, B Chain, c peptide, signal peptide * pre proinulin enters through RER * signal peptide is removed * remaining pp= proinsulin * disulfide bridges form between A chain & B chain * Proinsulin is packaged into vesicle -> golgi * C peptide is removed * mature insulin remains
22
Proteasomes function
uneeded/damaged proteins are broken down & recycled by hydrolysis => cell can maintain AA conc. & supply
23
Translation baby language
* mRNA binds to ribosome. * tRNA brings amino acids to ribosome. * Peptide bonds form between amino acids. * Ribosome moves along mRNA until stop codon reached.
24
Outline the structure and function of the promoter regions of DNA.
* short DNA sequence (typically TATA box) * binding site for RNA polymerase and other transcription factors * initiating transcription of the gene
25
Describe the initiation of transcription, including the role of the promoter sequence, transcription factors, and RNA polymerase.
* transcription factors bind to the promoter region of a gene * RNA polymerase at the start site * unwinds the DNA * synthesizes mRNA from the template strand in the 5' to 3' direction.
25
Activator sequences
bind activator proteins that increase transcription of a gene.
26
Repressor sequences
bind repressor proteins, which decrease or inhibit transcription
27
transcription factors
proteins that bind to specific DNA sequences, like the promoter, to initiate or regulate the process of transcription.
28
28
five functions of noncoding DNA sequences
Regulation of gene expression (e.g., promoters, enhancers). Splicing control (e.g., sites for spliceosomes). Structural roles (e.g., telomeres, centromeres). Developmental regulation (e.g., transcription factor binding sites). Reservoir for genetic variation.
29
location and timing of post-transcriptional modification of RNA.
* nucleus before mRNA leaves to the cytoplasm for translation. * 5' capping (methylguanosine cap). * Poly-A tail addition (adenine residues at the 3' end). * RNA splicing (removal of introns and joining of exons).
30
5' cap
* protects the mRNA from degradation * helps the mRNA bind to the ribosome for translation * helps in transporting the mRNA out of the nucleus.
31
poly-A tail.
* stability * mRNA lifespan.
32
RNA splicing
Spliceosome removes introns, and joins exons
33
reasons why proteins typically exist for a relatively short time within a cell.
* Rapid degradation via the proteasome system. * Changes in cellular conditions (e.g., stress). * The protein’s role in short-term functions. * Post-translational modifications signaling degradation.
34
role of activating enzymes in translation
* ATP hydrolysis provides energy for AA attachement * attach specific AA to 3' end * done repeatedly
35

IB Bio HL (23 decks)

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