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IB Biology - Theme D : Community and Change > D1.2 protein synthesis > Flashcards

D1.2 protein synthesis Flashcards

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1
Q

DNA and Protein Production

A

DNA controls protein production via sequences determining amino acids. Ribosomes in the cytoplasm synthesize proteins based on DNA instructions.

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2
Q

Transcription and Translation

A

DNA codes proteins through transcription (DNA to mRNA) and translation (mRNA to proteins) processes at ribosomes.

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3
Q

Genetic Code Characteristics

A

DNA ensures reliability in protein synthesis while allowing variability for evolution within a population.

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4
Q

DNA Communication

A

DNA sends instructions to ribosomes via RNA to regulate protein production. RNA serves as the messenger from the nucleus to the cytoplasm.

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5
Q

Gene Definition

A

Genes are specific DNA segments that encode proteins, found at particular locations in the DNA molecule.

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6
Q

Transcription

A

During transcription, DNA unzips at the gene site, genetic information from DNA is used to create a complementary RNA molecule, specifically messanger RNA (mRNA). this occurs in the cells nucleus and its cruical forprotein synthesis

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7
Q

Transcription

A

information carried by mRNA is used to build a correspondong protein. it takes place on the ribosomoes on the cytoplasm. during translation, (tRNA) transfer RNA molecules bring specific amino acids to the ribosomes, guided by mRNA condons, and a polypeptide chain is synthesised based on the genetic code.

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8
Q

DNA Stability

A

DNA remains stable and can serve as an RNA template without altering its base sequence, crucial for non-dividing cells like nerve cells.

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9
Q

Factors Affecting DNA Stability

A

Free radicals, chemicals, cigarette smoke, and UV radiation can compromise DNA stability. Specialized proteins exist to detect and repair such damage. Permanent changes, mutations, can impact protein production, but not all mutations are harmful; some can aid species’ efficiency or survival.

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10
Q

Transcription and Gene Expression

A

Transcription, the first step in gene expression, controls gene activity. Different genes are expressed at distinct times and developmental stages, allowing for gene expression regulation in organisms.

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11
Q

What are the four major types of RNA involved in protein synthesis?

A

Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Adension Triphosphate

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12
Q

Messenger RNA (mRNA):

A

Carries genetic information from nucleus DNA to ribosomes.

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13
Q

Transfer RNA (tRNA):

A

coordinates amino acids in the correct order of growing chain of amino acids.

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14
Q

Ribosomal RNA (rRNA):

A

Combines with proteins to form cytoplasmic ribosomes.

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15
Q

Adensione Triphosphate

A

ATP: single nucleotide of nucleic acid used in cells as a type of chemical energy

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16
Q

What role do codons and anticodons play in protein synthesis?

A

Codons:
Sequences of three nucleotides in mRNA that code for amino acids or signal the start/stop of protein synthesis. Serve as the genetic code during protein synthesis, determining the amino acid sequence.

Anticodons:

Complementary three-nucleotide sequences in tRNA. Pair with mRNA codons during translation, ensuring accurate amino acid incorporation into the growing polypeptide chain.

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17
Q

What are the characteristics of the genetic code?

A

The genetic code operates in triplets (three bases), coding for 20 amino acids.

With four possible mRNA bases (A, U, C, G), three bases yield 64 combinations, enough for all amino acids.

The code is degenerate, allowing multiple codons for the same amino acid.

Universality means most organisms share the same code, enabling genetic engineering across species.

Despite being degenerate, each codon consistently codes for the same amino acid or control signals.

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18
Q

What are the key features of the genetic code table?

A

Start codon: AUG, encoding methionine, initiates protein synthesis.

Three stop codons (UAA, UAG, UGA) signal the end of polypeptide chains.

The third position of mRNA codons determines specific amino acids in the protein sequence.

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19
Q

what is the role of RNA polymerase?

A

the role of RNA polymerase is to transcribe DNA into RNA by reading the DNA template strand and catalysing the synthesis of complementary RNA molecule

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20
Q

Transcription
what and where

A

genetic code of DNA copied into mRNA in the nucleus of the cell

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21
Q

transcription
how/ detail

A
  1. the enzyme RNA polymerase binds to DNA at the start of the gene
  2. theRNA polymerase moves along seperating the 2 strand of DNA
  3. RNA nucleotides pair up with complementary bases on DNA​
  4. Covalent bonds are formed between RNA nucleotides​
  5. The DNA strands rejoin behind the RNA polymerase as it moves along​
  6. RNA polymerase continues until it reaches a STOP codon. mRNA is released
  7. mRNA leaves the nucleus through a nuclear pore
22
Q

Translation
what and where

A

mRNA translated by ribosome into protein on a ribosome in the cyptoplasm

23
Q

Translation
how/ detail

A
  1. In the cytoplasm, a ribosome attaches to the START codon on the mRNA​
  2. A tRNA with a complementary anticodon moves to the ribosome. The tRNA carries a specific amino acid.​
  3. The next complementary tRNA moves to the next codon so there are two tRNAs side by side​
  4. A peptide bond forms between the two amino acids being carried by the tRNAs​
  5. The first tRNA is released and a 3rdone binds​
  6. 15 amino acids can be added to the chain PER SECOND!​
  7. A polypeptide is formed when the ribosome reaches a STOP codon​
24
Q

How do mRNA and tRNA work together in protein synthesis?

A

mRNA and tRNA cooperate in protein synthesis, holding positions, forming peptide bonds, and coordinating interactions

25
Q

Explain the involvement of tRNA and mRNA in ribosome functioning.

A

tRNA carries amino acids and binds to mRNA via complementary base pairing.

mRNA binds to the small ribosomal subunit, while tRNA binds to the large subunit.

Ribosome complex coordinates the interaction between tRNA and mRNA.

26
Q

How does the ribosome assemble the correct sequence of amino acids?

A

tRNA anticodons pair with mRNA codons to form the correct amino acid sequence.
Ribosome moves along mRNA, decoding one codon at a time to assemble the polypeptide chain.

27
Q

What process occurs until the entire polypeptide chain is formed?

A

Continuous cycle of events involving mRNA movement through the ribosome.
tRNA anticodons base pair with mRNA codons to create the required amino acid sequence.

28
Q

What is a point mutation, and how does it affect proteins?

A

Point mutation: Involves a change in a single base of a gene, altering transcription and protein structure.

Example: Sickle-cell disease caused by a single point mutation affecting haemoglobin, leading to altered protein shape.

29
Q

What is sickle-cell disease, and how does it impact red blood cells?

A

Sickle-cell disease: Caused by a point mutation in haemoglobin gene, changing the protein shape.
Altered haemoglobin leads to deformed red blood cells, hindering blood flow and causing health issues.

30
Q

How do DNA replication, transcription, and translation proceed directionally?

A

DNA replication: DNA polymerase assembles the new strand in a 5’ to 3’ direction.
Transcription: RNA polymerase adds 5’ ends of RNA nucleotides to the 3’ end of the growing RNA molecule.
Translation: mRNA is read from 5’ to 3’ direction to synthesize the polypeptide chain at the ribosome.

31
Q

What is the role of the promoter in transcription?

A

The promoter region determines the template strand for transcription in a gene.
It’s a short sequence of bases that doesn’t get transcribed itself.
In bacteria, RNA polymerase attaches directly to the promoter to initiate transcription.
In eukaryotic cells, transcription factors bind to the promoter first, then recruit RNA polymerase to start transcription.

32
Q

What are transcription factors and their role in gene regulation?

A

Proteins regulating gene transcription.
Control gene activity in cells.
Assist RNA polymerase attachment.
Some activate, others prevent transcription.
Bind to specific DNA sequences.

33
Q

What are the key sections involved in transcription?

A

Promoter
Transcription unit
Terminator
Transcription bubble moves from promoter to terminator

34
Q

What are examples of DNA sequences that do not code for proteins?

A

Regulators of gene expression: promoters, enhancers, silencers, and insulators
Genes for rRNA and tRNA formation
Telomeres: protective ends of chromosomes
Introns: non-coding sections removed from primary mRNA

35
Q

What are introns and exons in eukaryotic DNA?

A

Introns: Non-coding stretches within protein-coding regions.

Exons: Coding sequences that remain after splicing removes introns from pre-mRNA to form functional mRNA in eukaryotes.

36
Q

What are spliceosomes and their role in gene expression?

A

Spliceosomes: Comprised of small nuclear RNAs and proteins.
Role: Facilitate intron removal from primary mRNA, enabling rearrangement of exons, leading to diverse protein production. They assist in joining the remaining exons.

37
Q

What are the structural elements present at the ends of mature mRNA?

A

5’ end: Contains a cap made of a modified guanine nucleotide with three phosphates.
3’ end: Features a polyA tail composed of 50-250 adenine nucleotides.
Function: These elements stabilize mature mRNA, protecting it from degradation in the cytoplasm, and aid in the translation process at the ribosome.

38
Q

What is alternative splicing in genetics?

A

Definition: A process in eukaryotic cells where different mature mRNA transcripts are generated from a single primary mRNA transcript by including different exons.
Function: Increases the diversity of proteins produced from one gene.
Significance: Plays a role in complex biological processes, particularly during cardiac development and disease.

39
Q

How does alternative splicing impact cardiac troponin T (cTnT) gene expression?

A

cTnT Gene: Active in heart (cardiac) muscle.
Foetal vs. Adult: Foetal cardiac muscle includes an exon absent in adult cardiac muscle.
Effect: The included exon in foetal muscle increases heart sensitivity to calcium compared to the adult.

40
Q

Where does decoding mRNA to produce a polypeptide occur?

A

Location: Between the two subunits of the ribosome.

Binding Sites: Space contains binding sites for mRNA and three tRNA binding sites.

Process: Decodes mRNA into a polypeptide during protein synthesis.

41
Q

How does the polypeptide chain assemble?

A

Direction of Assembly: 5’ to 3’ direction at the ribosome.
Starting Amino Acid: Always begins with methionine (Met).
Reasoning: AUG codon serves as the start codon, binding specifically with methionine.

42
Q

What’s the precursor of insulin, and where is it produced?

A

Insulin Precursor:
Pre-proinsulin.
Produced in pancreatic beta cells.

43
Q

What happens to pre-proinsulin when it enters the endoplasmic reticulum?

A

endoplasmic Reticulum:
Signal peptide removal.
Produces proinsulin.

44
Q

What process yields the mature form of insulin from proinsulin?

A

enzymatic removal of C peptide from proinsulin.

45
Q

Describe the structure of mature insulin.

A

Composed of two chains.
Held together by disulfide bonds.

46
Q

How is mature insulin packaged and secreted?

A

packaged in Golgi apparatus.
Secreted via exocytosis into the bloodstream.

47
Q

What role do molecular chaperones play in protein folding?

A

Aid in protecting proteins during folding.
Shield from interference that hampers folding.

48
Q

What’s the function of disulfide bond formation in proteins?

A

Stabilize tertiary and quaternary protein structures.
Essential for protein stability.

49
Q

Define glycosylation and its role in polypeptides.

A

Addition of carbohydrate side chains to polypeptides.
Prevents protein clumping, ensuring proper function.

50
Q

What is the proteome?

A

Total set of proteins expressed by a cell, tissue, or organism.
Includes synthesized, degraded, and functional proteins

51
Q

How do proteases function in protein degradation?

A

Enzymes degrading proteins by breaking peptide bonds.
Convert proteins into individual amino acids.

52
Q

Explain the role of ubiquitin in cellular protein disposal

A

Damaged/unneeded proteins marked with ubiquitin.
Signal for cellular destruction of marked proteins.

IB Biology - Theme D : Community and Change (12 decks)

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