Physiology Chapter 3

Questions and Answers

What is the role of RNA polymerase in the synthesis of RNA?

It binds amino acids to forming proteins.

It moves along the DNA strand to build the RNA molecule. (correct)

It creates DNA from RNA templates.

It transports RNA from the nucleus to the cytoplasm.

Which of the following sequences represents the RNA codons controlling the attachment of amino acids?

CCG, AUC, GAC

CCG, UCU, GAA (correct)

UCU, GAA, ACG

GGC, UAU, CAA

What is the process of transferring code from DNA to RNA called?

Replication

Transcription (correct)

Translocation

Translation

What type of energy is utilized during the activation of RNA synthesis?

High-energy phosphate bonds from ATP Signup and view all the answers

After RNA is synthesized, where does it primarily diffuse to for protein synthesis?

The cytoplasmic compartment Signup and view all the answers

During RNA formation, what happens to the last two phosphates on a nucleotide?

They combine with the nucleotide through high-energy phosphate bonds. Signup and view all the answers

Which amino acids are indicated to be added to the growing RNA chain based on the provided codons?

Proline, Serine, and Glutamic acid Signup and view all the answers

What intermediary nucleic acid is formed that controls protein synthesis?

mRNA Signup and view all the answers

What role does peptidyl transferase play during protein synthesis?

It catalyzes the formation of peptide bonds between amino acids. Signup and view all the answers

How does tRNA contribute to protein synthesis?

By carrying amino acids to the ribosome in correct sequence. Signup and view all the answers

Which substances are synthesized during the metabolic processes discussed?

Lipids, amino acids, and nucleotides. Signup and view all the answers

What is implied about the relationship between genes and cellular functions?

Genes control both physical and biochemical functions of the cells. Signup and view all the answers

In the context of transcription and translation, what function does mRNA serve?

It provides the template for the sequence of amino acids. Signup and view all the answers

What enzyme assists in the assembly of the RNA-induced silencing complex (RISC)?

Dicer Signup and view all the answers

Which structures are formed from clusters of ribosomes engaged with a single mRNA?

Polyribosomes Signup and view all the answers

What are the characteristics of pre-miRNAs?

70-nucleotide stem-loop structures Signup and view all the answers

How do miRNAs regulate gene expression?

By repressing translation or promoting mRNA degradation Signup and view all the answers

In which part of the cell are pri-miRNAs processed into pre-miRNAs?

Cell nucleus Signup and view all the answers

What is the result of mRNA binding to miRNAs?

Repression of translation Signup and view all the answers

Which type of ribosomal structure allows for multiple proteins to be formed simultaneously?

Polyribosomes Signup and view all the answers

What is the primary role of the dicer enzyme in RNA processing?

To convert pre-miRNAs into miRNAs Signup and view all the answers

During which phase of the cell cycle are centrioles typically replicated?

During interphase Signup and view all the answers

What is the primary structural composition of the centrioles?

Nine parallel tubular structures Signup and view all the answers

What is the approximate size of each centriole?

0.4 micrometers in length and 0.15 micrometers in diameter Signup and view all the answers

How do the pairs of centrioles position themselves before mitosis?

They move apart at right angles Signup and view all the answers

What is the relationship between the number of mutations expected between generations and the number of genes in the human genome?

Approximately 10 mutations are expected for many thousands of genes Signup and view all the answers

What structure, along with centrioles, is referred to as a centrosome?

Pericentriolar material Signup and view all the answers

What initiates the movement of centrioles apart from each other during mitosis?

Polymerization of protein microtubules Signup and view all the answers

Why is it beneficial for humans to have two separate sets of chromosomes?

To ensure one functional gene is available despite mutations Signup and view all the answers

What occurs to most proteins synthesized by ribosomes in non-glandular cells?

They are released directly into the cytosol. Signup and view all the answers

What chemical change facilitates the formation of peptide linkages during protein synthesis?

Removal of a hydroxyl radical and a hydrogen atom. Signup and view all the answers

Which of the following best describes the role of ATP in protein synthesis?

ATP activates amino acids by forming an adenosine monophosphate complex. Signup and view all the answers

What is primarily formed as a byproduct of peptide bond formation?

Water. Signup and view all the answers

What is the significance of protein enzymes formed in cells?

They facilitate almost all chemical reactions within the cell. Signup and view all the answers

In the context of amino acid activation, what happens to high-energy phosphate bonds?

They are released during the activation process. Signup and view all the answers

Which molecules are typically involved in forming protein-containing secretory vesicles?

Large amounts of protein and RNA. Signup and view all the answers

What is the immediate consequence of removing a hydroxyl radical and a hydrogen atom during peptide bond formation?

Formation of a dipeptide and release of water. Signup and view all the answers

What is the role of DNA polymerases during DNA proofreading?

They cut out defective DNA areas. Signup and view all the answers

What is created after DNA replication before the onset of mitosis?

Chromatids Signup and view all the answers

What process describes the occurrence of mistakes in DNA sequences?

Mutation Signup and view all the answers

What is the consequence of a mutation in the DNA sequence?

Production of an abnormal protein Signup and view all the answers

In what timeframe does mitosis typically follow DNA replication?

Within hours Signup and view all the answers

What role do DNA ligases play in DNA repair?

They join together DNA strands. Signup and view all the answers

What is the primary function of small interfering RNA (siRNA)?

To silence the expression of specific genes Signup and view all the answers

What characterizes the chromatids after DNA replication?

They are attached at the centromere. Signup and view all the answers

Which enzyme is specifically involved in generating primers during DNA replication?

DNA primase Signup and view all the answers

What is the length range of small interfering RNA (siRNA) molecules?

20 to 25 nucleotides Signup and view all the answers

Which statement correctly describes pri-miRNA in the context of miRNA generation?

It serves as the primary transcript for the generation of miRNAs Signup and view all the answers

How do small interfering RNAs (siRNAs) typically originate?

From the processing of pre-miRNAs Signup and view all the answers

What distinguishes miRNAs from small interfering RNAs (siRNAs) in their functional roles?

miRNAs usually regulate gene expression post-transcriptionally, whereas siRNAs are used for gene silencing Signup and view all the answers

Which enzyme is responsible for relieving the torsional strain during DNA replication?

Topoisomerase Signup and view all the answers

What is the main difference between the leading and lagging strands during DNA replication?

The leading strand synthesizes continuously while the lagging strand synthesizes in fragments. Signup and view all the answers

What is the role of primers in DNA replication?

To provide a free 3' hydroxyl group for DNA polymerase to extend Signup and view all the answers

Which process is primarily responsible for the elongation phase of DNA replication?

Polymerization Signup and view all the answers

What structural feature of DNA indicates the directionality of its strands?

Antiparallel orientation Signup and view all the answers

What component is not involved in the synthesis of the lagging strand?

Topoisomerase Signup and view all the answers

What is the role of helicase during DNA replication?

To unwind the double helix Signup and view all the answers

What occurs to the newly synthesized DNA strands as the replication fork progresses?

They remain attached to the parent strand Signup and view all the answers

What role do enhancers play in the transcription of genes in eukaryotes?

They can bind transcription factors that regulate the gene's expression. Signup and view all the answers

How do transcription factors affect the transcription process?

They increase the likelihood that RNA polymerase will synthesize RNA. Signup and view all the answers

Why must DNA be decompacted for transcription to occur?

Decompaction allows RNA polymerase to bind effectively. Signup and view all the answers

Where can enhancers be located in relation to the genes they regulate?

In varying distances, potentially on different chromosomes. Signup and view all the answers

What is the approximate number of gene enhancer sequences in the human genome?

Over 100,000. Signup and view all the answers

What is required for partial RNA transcription to occur in a decompacted DNA region?

Specific transcription factors to control the transcription rate. Signup and view all the answers

What holds the DNA in a compacted state within chromosomes?

Proteins such as histones. Signup and view all the answers

How does the compacted state of DNA affect its function?

It prevents the formation of RNA. Signup and view all the answers

What are the two types of bases that connect the DNA strands?

Purines and pyrimidines Signup and view all the answers

Which of the following sugars is involved in DNA structure?

Deoxyribose Signup and view all the answers

Which components make up the outside strands of DNA?

Phosphoric acid and deoxyribose Signup and view all the answers

What role do purine and pyrimidine bases play in DNA?

They determine the genetic code Signup and view all the answers

Which of the following pairs correctly identifies the two purines in the DNA structure?

Adenine and Guanine Signup and view all the answers

What characteristic distinguishes pyrimidines from purines in DNA?

Pyrimidines consist of a single-ring structure Signup and view all the answers

Which of the following correctly identifies the structure comprised of phosphoric acid and deoxyribose?

Sugar-phosphate backbone Signup and view all the answers

What is the primary function of phosphoric acid in the DNA structure?

To link sugar molecules Signup and view all the answers

Study Notes

RNA Polymerase and Transcription

RNA polymerase moves along the DNA, synthesizing RNA molecules.
RNA codons (CCG, UCU, GAA) correspond to specific amino acids: proline, serine, and glutamic acid.
The process of transcription transfers genetic information from DNA to RNA.

Protein Synthesis Process

RNA diffuses from the nucleus to the cytoplasm through nuclear pores.
Protein synthesis is regulated by RNA, particularly messenger RNA (mRNA).
Microprocessor complex processes pri-miRNAs into pre-miRNAs (70-nucleotide structures).
Dicer enzyme generates miRNAs, which regulate gene expression by binding to mRNA.

Ribosomes and Polyribosomes

Ribosomes can synthesize proteins without specificity; any ribosome may produce any protein.
Polyribosomes (clusters of 3 to 10 ribosomes) can simultaneously translate a single mRNA strand.
Proteins synthesized by ribosomes largely enter the cytosol, not the endoplasmic reticulum, except in glandular cells.

Peptide Linkage

Peptide linkage is formed between amino acids during protein synthesis through the removal of a hydroxyl radical and a hydrogen ion.
Each amino acid is activated and converted into an amino acid-tRNA complex through ATP energy.

Enzymatic Actions in Cell Metabolism

Thousands of protein enzymes synthesized control various cell reactions.
These enzymes facilitate the synthesis of lipids, glycogen, purines, pyrimidines, and other substances.

Gene Function and Biochemical Activity

Genes regulate both physical and chemical cellular functions.
Activation of genes determines cellular activities and responses.

Chromosomes and Genetic Mutations

Humans possess 46 chromosomes, arranged in 23 pairs.
Genetic mutations occur frequently during reproduction, as many as 10 per generation due to mutations.
Each individuality has two chromosome sets from parents, providing a backup for functional genes to mitigate mutations.

Centrioles and Cell Division

Centrioles, cylindrical structures measuring approximately 0.4 micrometers long, are replicated during interphase.
Centrioles are organized in pairs, positioned at right angles, and play a crucial role during cell division.

Centrosome Function

The centrosome consists of a pair of centrioles plus pericentriolar material.
Prior to mitosis, centrioles move apart, driven by microtubule polymerization, facilitating the process of cell division.

DNA Structure and Components

DNA strands consist of phosphoric acid and deoxyribose sugar.
Purine and pyrimidine bases form internal connections, playing a key role in genetic coding.
Purines: Adenine (A), Guanine (G)
Pyrimidines: Cytosine (C), Thymine (T)

MicroRNA (miRNA) and Gene Regulation

miRNAs are primary gene transcripts involved in protein synthesis regulation.
Small interfering RNA (siRNA) consists of 20 to 25 nucleotides and silences specific gene expression.
siRNAs can be synthetic and are administered for gene silencing.

Transcription and Gene Expression

Gene transcription in eukaryotes is influenced by enhancers, which are DNA regions that bind transcription factors.
Enhancers can be located far from the genes they regulate, including on different chromosomes.
Estimates indicate over 100,000 gene enhancer sequences in the human genome.

DNA Replication

DNA replication occurs at the replication fork involving leading and lagging strands.
Enzymes involved: Topoisomerase, Primase, DNA polymerase, Ligase, and Helicase.
Primers generated by DNA primase initiate the replication process.

DNA Proofreading and Repair

DNA proofreading occurs post-replication, correcting mismatched nucleotides using specific enzymes.
Enzymes involved in repair: DNA polymerases and ligases.
Mutations arise from errors in replication, potentially resulting in abnormal proteins and impaired cell function.

Cell Mitosis

Mitosis separates replicated chromosomes, forming two new cells.
Duplicated chromosomes, called chromatids, attach at the centromere during mitosis.
Mitosis typically follows replication within 1-2 hours in many cells.

Central Role in Cell Function

DNA must be decompacted for transcription; this process is regulated by transcription factors.
Chromatin structure and location affect gene expression patterns in various tissues.

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Description

This quiz focuses on the role of RNA polymerase in the synthesis of RNA molecules from a DNA template. You'll also explore the significance of various RNA codons and their functions in protein synthesis. Test your understanding of these essential biological processes.