Genetics Ch.14- Translation and Proteins

Flashcards covering key concepts from Chapter 14 on Translation and Proteins in Genetics.

What is the biological process of assembling amino acids into polypeptide chains called?

Translation

What are the three types of molecules required for translation?

Amino acids, messenger RNA (mRNA), ribosomes, and transfer RNA (tRNA)

What is the function of tRNA in translation?

tRNAs adapt genetic information present as specific triplet codons in mRNA to corresponding amino acids.

What are ribosomes composed of?

Ribosomal proteins and ribosomal RNAs (rRNAs).

What is the size of prokaryotic ribosomes?

70S

What is the size of eukaryotic ribosomes?

80S

What does rDNA stand for?

Ribosomal DNA.

What is a characteristic structure of tRNA?

Cloverleaf structure.

What is the role of the anticodon in tRNA?

The anticodon base-pairs with the codon in mRNA.

What is aminoacylation?

The process of chemically linking tRNA molecules to their respective amino acids.

What catalyzes the aminoacylation reaction?

Aminoacyl tRNA synthetase.

What does the initiation of translation require?

Small and large ribosomal subunits, mRNA molecule, GTP, charged initiator tRNA, and initiation factors.

What is the function of release factors in termination?

Stimulates hydrolysis of polypeptide from peptidyl tRNA.

What are polysomes?

mRNAs with several ribosomes translating at once.

How does eukaryotic translation differ from prokaryotic translation?

Eukaryotic translation is more complex and requires more factors for initiation, elongation, and termination.

What is the function of the Kozak sequence?

Increases efficiency of translation by interacting with initiator tRNA.

What is the result of posttranslational modifications?

Changes to a polypeptide chain that are crucial for the functional capability of the final protein product.

What determines the type of amino acid?

The R group (side chain) bound to the central carbon atom of the amino acid.

What bond forms between two amino acids?

Peptide bond.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary.

What does primary protein structure refer to?

The sequence of amino acids in a polypeptide chain.

What is the secondary structure of proteins?

Local folding into structures such as alpha-helices and beta-pleated sheets.

What is involved in the tertiary structure of proteins?

The overall three-dimensional conformation of a single polypeptide chain.

What does quaternary structure refer to in proteins?

A protein structure composed of more than one polypeptide chain.

What can happen to proteins that are misfolded?

They can lead to diseases, such as Creutzfeldt–Jakob disease.

What role do proteins play in the body?

They perform diverse roles such as transport, structure, enzymatic activity, and immune defense.

What type of proteins transport oxygen in the body?

Hemoglobin and myoglobin.

What are hydrophobic amino acids characterized by?

They have nonpolar side chains.

What are hydrophilic amino acids characterized by?

They have polar side chains.

What type of reaction forms a peptide bond?

Dehydration (condensation) reaction.

What are chaperones?

Proteins that facilitate the folding of other proteins.

What is the main function of enzymes in biological systems?

To catalyze chemical reactions and lower the activation energy.

What do immunoglobulins do in vertebrates?

They function in the immune system.

What are peptides and their relationship to proteins?

Peptides are precursors to proteins and are assembled from amino acids.

What role do transport proteins play in the cell?

They facilitate the movement of molecules across membranes.

What is the function of transcription factors?

Regulate gene expression.

What does the term 'polypeptide' refer to?

A polymer of amino acids linked by peptide bonds.

What is the primary role of structural proteins?

To provide support and structure to cells and tissues.

How does the structure of collagen contribute to its function?

Collagen provides strength and support in connective tissues.

What do actin and myosin proteins do?

They are involved in muscle contraction.

How does protein structure influence its function?

Variations in protein structure provide the basis for biological diversity.

What is the role of carbohydrates in protein modification?

They can be attached as side chains in glycoproteins.

What is the significance of posttranscriptional modifications?

They can alter the stability and functionality of mRNA.

What are the consequences of protein misfolding?

It can lead to loss of function and diseases.

How do proteins get their functional state after synthesis?

Through the process of protein folding.

What can occur during the elongation phase of translation?

Peptide bonds form between amino acids as the ribosome moves along mRNA.

What three-dimensional shape does a protein assume?

The shape is key to its function and stability.

What is the overall effect of translation in cells?

Synthesis of proteins based on the genetic code.

What is the function of the poly-A tail in eukaryotic mRNA?

It enhances the stability of the mRNA and regulates translation.

What are the roles of initiation factors in protein translation?

They assist in the assembly of the ribosomal complex and initiation of translation.

What is GTP's role in translation?

It provides energy for various stages of translation.

What can trigger the termination of translation?

The presence of stop codons in the A site.

How do ribosomes contribute to protein synthesis?

They serve as the site where mRNA is translated into polypeptides.

What is the purpose of having multiple ribosomes on a single mRNA strand?

To efficiently produce many copies of a protein from a single mRNA template.

What determines the specificity of tRNA for an amino acid?

The unique aminoacyl tRNA synthetase that links tRNA to its corresponding amino acid.

How does the structure of tRNA facilitate its role in protein synthesis?

Its cloverleaf shape allows it to correctly base-pair with mRNA codons.

What is the significance of codons in mRNA?

They specify the sequence of amino acids in a polypeptide.

Why are ribosomes described as 'molecular machines'?

They carry out the process of translating mRNA into proteins.

What is the difference between primary and secondary structures of proteins?

Primary structure refers to the amino acid sequence, while secondary structure refers to local folded structures.

What do molecular chaperones assist with?

They assist in the proper folding of proteins.

What factor is crucial for the translation initiation complex to form in eukaryotes?

The presence of the 5' cap and poly-A tail.

What is the primary purpose of posttranslational modifications?

To ensure proper protein functioning and specificity.

What type of proteins are histones and what is their function?

They bind to DNA in eukaryotic cells and help regulate gene expression.

What is the role of enzymes as proteins?

They catalyze and accelerate chemical reactions within biological systems.

What are the key features of enzymes?

They lower activation energy and increase reaction rates.

What do signaling proteins do in cellular communication?

They transmit signals to elicit specific responses in cells.

What is the role of the endoplasmic reticulum in eukaryotic translation?

It is involved in the translation of proteins that are secreted or inserted into membranes.

How does open-loop translation differ from closed-loop translation in eukaryotes?

In closed-loop translation, mRNA forms a loop due to interaction between the cap and poly-A tail.

What is the requirement for ribosomal subunit assembly in translation initiation?

Both small and large ribosomal subunits must assemble together.

What is an example of a posttranslational modification?

The addition of carbohydrate side chains to proteins.

What is the importance of the 7-methylguanosine cap on mRNA?

It plays a critical role in the initiation of translation.

How are eukaryotic proteins generally processed after translation?

They undergo various modifications and folding to become functional.

What phenomenon illustrates the relationship between codons and amino acids?

The genetic code.

What distinguishes the polypeptide chains of different proteins?

The specific sequence and composition of amino acids.

What is the composition of the ribosome’s active site?

It typically contains rRNA that catalyzes peptide bond formation.

How do proteins participate in metabolic processes?

They serve as enzymes, substrates, or regulators within metabolic pathways.

Why are amino acids considered the building blocks of proteins?

They are linked together in specific sequences to form polypeptides.

What impact do variations in protein structure have on organisms?

They contribute to the diversity of functions and traits among organisms.

How does protein folding affect disease development?

Improper folding can lead to dysfunction and associated diseases.

What enzymes are responsible for forming peptide bonds?

The ribosomal RNA (rRNA) within the ribosome during translation.

What two factors must align for effective tRNA function?

The correct amino acid must be attached to the tRNA and the tRNA must correctly fit the mRNA codon.

What is one function of signal sequences in proteins?

They direct the transport of proteins to their proper cellular locations.