Guyton Physiology C1-8

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Questions and Answers

What is the primary function of ribosomes attached to the granular ER?

Transportation of ER vesicles

Modification of lysosomes

Synthesis of lipids

Synthesis of proteins (correct)

Which structures serve as the site for the processing of materials that enter from the ER?

Nucleus

Golgi apparatus (correct)

Lysosomes

Mitochondria

What type of ER does not have attached ribosomes and is involved in lipid synthesis?

Agranular ER (correct)

Transitional ER

Rough ER

Granular ER

What role do lysosomes play in the cell?

Intracellular digestion Signup and view all the answers

How are substances transported from the ER to the Golgi apparatus?

Via transport vesicles Signup and view all the answers

Which of the following is NOT a component formed by the Golgi apparatus?

Cell membranes Signup and view all the answers

What happens when the membranes surrounding lysosomes are damaged?

Digestive enzymes are released Signup and view all the answers

What type of energy sources do mitochondria primarily utilize?

Carbohydrates, fats, and proteins Signup and view all the answers

What is the primary function of nucleoli within the nucleus?

Synthesis of ribosomal RNA Signup and view all the answers

What is the approximate diameter of nuclear pores?

100 nanometers Signup and view all the answers

Which type of endocytosis is responsible for the ingestion of extracellular fluid?

Pinocytosis Signup and view all the answers

Which of the following best describes the process of phagocytosis?

Ingestion of large particles through membrane invagination Signup and view all the answers

In which structures are ribosomal RNA found prior to being transported to the cytoplasm?

Nucleoli Signup and view all the answers

Which type of membrane protein is found on the inside of the membrane beneath coated pits?

Clathrin Signup and view all the answers

What initiates the process of phagocytosis?

Interaction between receptors and surface proteins of the particle Signup and view all the answers

Which cells are particularly known for their ability to perform phagocytosis?

Tissue macrophages and white blood cells Signup and view all the answers

What is the sequence of three successive bases in a DNA strand called?

Code word Signup and view all the answers

Which process transfers the DNA code to RNA?

Transcription Signup and view all the answers

What type of sugar is found in RNA?

Ribose Signup and view all the answers

During RNA synthesis, what is formed from the complementary base pairing with DNA code triplets?

Codons Signup and view all the answers

What do the code triplets in DNA dictate?

The sequence of amino acids in a protein Signup and view all the answers

How are the nucleotides activated for RNA synthesis?

Through the addition of two phosphate radicals Signup and view all the answers

What is the primary role of RNA after it is synthesized in the nucleus?

To control protein synthesis in the cytoplasm Signup and view all the answers

What replaces thymine in RNA?

Uracil Signup and view all the answers

What is the primary role of cilia in the respiratory system?

To create a layer of mucus and clear passages Signup and view all the answers

Which of the following factors is essential for the proper functioning of cilia?

Appropriate ionic conditions Signup and view all the answers

What mechanism describes the movement of the ovum in the uterine tubes?

Whiplike motion of cilia Signup and view all the answers

How does gene expression influence cellular functions?

By controlling the synthesis of proteins Signup and view all the answers

Which statement accurately describes the two primary components necessary for ciliary movement?

ATP availability and ionic conditions Signup and view all the answers

Which component primarily catalyzes the conversion of ADP to ATP in the mitochondria?

ATP synthetase Signup and view all the answers

What is the initial substrate for ATP production via glycolysis?

Glucose Signup and view all the answers

In the citric acid cycle, acetyl-CoA is primarily split into which two components?

Hydrogen ions and carbon dioxide Signup and view all the answers

Which cellular function does ATP NOT directly support?

Photosynthesis Signup and view all the answers

What is the ultimate fate of hydrogen ions produced during the citric acid cycle?

They combine with oxygen to form water. Signup and view all the answers

Which process occurs after glycolysis and prior to the citric acid cycle?

Conversion to acetyl-CoA Signup and view all the answers

Which enzyme is involved in the final step of ATP formation through the chemiosmotic mechanism?

ATP synthetase Signup and view all the answers

What percentage of ATP is produced through glycolysis in a typical cell?

Less than 5% Signup and view all the answers

What is the main role of cilia in the uterine tubes?

To generate movement of fluid towards the uterine cavity Signup and view all the answers

Which factor is NOT necessary for the proper functioning of cilia?

High temperature environments Signup and view all the answers

How do genes control protein synthesis in the cell?

Through the control of RNA formation and subsequent protein translation Signup and view all the answers

What is the approximate movement rate of mucus in the nasal cavity due to ciliary action?

1 cm/min Signup and view all the answers

What is the term for the entire process from the transcription of genetic code to the formation of proteins?

Gene expression Signup and view all the answers

What is the estimated number of different proteins produced by various cell types in humans?

100,000 Signup and view all the answers

Which of the following correctly describes the structure of DNA?

Double-stranded helical molecule Signup and view all the answers

What type of nucleotides can be formed from the four nitrogenous bases?

Nucleotides Signup and view all the answers

During DNA formation, adenine pairs with which nitrogenous base?

Thymine Signup and view all the answers

What is the backbone of each DNA strand composed of?

Alternating phosphoric acid and deoxyribose Signup and view all the answers

What role does transfer RNA (tRNA) play in protein synthesis?

It transports activated amino acids to the ribosomes. Signup and view all the answers

How are the strands of DNA held together?

Loose hydrogen bonds between bases Signup and view all the answers

What is formed during transcription from DNA?

Messenger RNA Signup and view all the answers

How does mRNA facilitate the formation of proteins within the ribosomes?

mRNA pairs with tRNA anticodons to determine amino acid sequence. Signup and view all the answers

What is the primary function of microRNA (miRNA) in cellular processes?

To regulate gene transcription and translation. Signup and view all the answers

Which of the following is NOT one of the basic building blocks of DNA?

Ribose Signup and view all the answers

What determines the specific amino acid that a tRNA molecule carries?

The unique anticodon triplet on the tRNA. Signup and view all the answers

What occurs when a stop codon is reached during protein synthesis?

The completed protein is released from the ribosome. Signup and view all the answers

How does the structure of ribosomes facilitate protein synthesis?

Ribosomes contain enzymes that link tRNA with amino acids. Signup and view all the answers

What specific process is described by the decoding of the mRNA genetic code into a polypeptide chain?

Translation Signup and view all the answers

What is the consequence if a tRNA molecule fails to recognize its corresponding mRNA codon?

The protein will be synthesized with an incorrect amino acid sequence. Signup and view all the answers

What role does sodium play in the transport of glucose and amino acids into cells?

It provides energy by its movement through a carrier protein. Signup and view all the answers

During calcium counter-transport, what direction do sodium and calcium ions move?

Sodium moves to the interior and calcium to the exterior. Signup and view all the answers

Which statement correctly defines the conformational change in transport proteins involved in sodium co-transport?

It requires binding of both sodium and glucose or amino acids. Signup and view all the answers

What is the primary mechanism behind the electrical potentials generated in nerve and muscle cells?

Concentration differences of ions across a selectively permeable membrane. Signup and view all the answers

In which part of the kidneys is hydrogen counter-transport especially significant?

Proximal tubules. Signup and view all the answers

What primarily drives the diffusion of potassium ions across the neuronal cell membrane?

High permeability of the membrane specifically to potassium ions. Signup and view all the answers

What occurs first in the sodium counter-transport mechanism involving hydrogen ions?

Sodium ions move into the tubular cells. Signup and view all the answers

How does sodium affect the transport of substances in counter-transport mechanisms?

It shifts ion concentrations to create the needed energy gradient. Signup and view all the answers

What is the primary mechanism by which saltatory conduction increases the speed of neuronal transmission?

Neuronal impulses jump between nodes of Ranvier. Signup and view all the answers

How much faster can saltatory conduction increase neuronal transmission velocity in myelinated fibers compared to unmyelinated fibers?

5-50 fold. Signup and view all the answers

What is the main advantage of saltatory conduction regarding energy efficiency?

It minimizes ion movement across thicker myelinated sheaths. Signup and view all the answers

What effect does the diameter of myelinated nerve fibers have on action potential conduction velocity?

Larger diameters yield higher conduction velocities. Signup and view all the answers

What percentage of body mass is primarily composed of skeletal muscle?

40 percent. Signup and view all the answers

Which two protein filaments are primarily responsible for the contraction of skeletal muscle?

Actin and myosin. Signup and view all the answers

What is the role of myofibrils within muscle fibers?

They facilitate muscle contraction. Signup and view all the answers

How many myosin filaments are typically present in each myofibril of skeletal muscle?

<ol start="1500"> <li></li> </ol> Signup and view all the answers

Study Notes

Protein Synthesis and Cellular Functions

Ribosomes attached to granular endoplasmic reticulum (ER) synthesize proteins using messenger RNA.
Synthesized proteins enter the Golgi apparatus, where they undergo modifications before being released or utilized.
The smooth ER (agranular) lacks ribosomes and synthesizes lipid substances and other cellular processes through intrareticular enzymes.
The Golgi apparatus is prominent in secretory cells, processing substances from the ER to form lysosomes and secretory vesicles.
Small transport vesicles (ER vesicles) continuously pinch off from the ER and fuse with the Golgi apparatus for substance transport.
Lysosomes are membrane-bound vesicles containing digestive enzymes that break down damaged cell structures, food particles, and bacteria.
Membrane integrity protects lysosomal enzymes from digesting other cellular substances until membrane damage occurs.
Mitochondria serve as energy production centers, converting glucose, fatty acids, and amino acids into ATP via oxidation reactions.
Ribosomal RNA is synthesized in the nucleolus, which enlarges during active protein synthesis.
Each cell's nuclear envelope has pores allowing RNA to exit into the cytoplasm for protein production.

Ingestion by the Cell

Cells utilize diffusion and active transport to obtain nutrients from surrounding fluids.
Endocytosis allows large particles to enter the cell, primarily through pinocytosis (ingestion of small fluid globules) and phagocytosis (ingestion of large particles).
Pinocytosis involves receptors on the membrane binding with molecules, triggering invagination and vesicle formation.
Phagocytosis is executed by specialized cells like macrophages and white blood cells, initiated by binding of particle molecules to phagocyte receptors.

ATP Production

Mitochondria generate most ATP through the citric acid cycle involving acetyl-CoA derived from pyruvic acid, fatty acids, and amino acids.
The citric acid cycle releases hydrogen ions and carbon dioxide; reactive hydrogen ions combine with oxygen, releasing considerable energy.
ATP synthesis occurs through the movement of hydrogen ions via ATP synthetase, converting ADP into ATP, which is distributed throughout the cell.
ATP is essential for various cellular functions, including membrane transport, chemical synthesis, and mechanical work (e.g., muscle contraction, ciliary motion).

Genetic Control of Protein Synthesis

Genes located in the cell nucleus direct protein synthesis, impacting cellular function.
DNA, a double-stranded helical molecule, encodes the formation of RNA, which carries the information for protein synthesis.
The process of gene expression encompasses transcription (DNA to RNA) and translation (RNA to protein).
Genetic code within DNA consists of sequences of three bases (code words) that dictate the arrangement of amino acids in proteins.
RNA synthesis occurs when a DNA strand separates and serves as a template for complementary RNA.
RNA nucleotides include adenine, guanine, cytosine, and uracil, with ribose replacing deoxyribose from DNA.
The activation of nucleotides involves adding phosphate groups, forming high-energy tri-phosphates crucial for RNA synthesis.

Ciliary Movement and Function

Cilia in the nasal cavity and lower respiratory airways move mucus towards the pharynx at approximately 1 cm/min, facilitating clearance of mucus and trapped particles.
In uterine tubes, cilia promote the transport of fluid, helping to move the ovum from the ovary to the uterus.
Ciliary movement requires adequate ATP and specific ionic conditions, including magnesium and calcium.

Genetic Control of Protein Synthesis

Genes in the cell nucleus regulate protein synthesis, controlling cell function and structure.
Each gene, a double-stranded DNA molecule, dictates the formation of ribonucleic acid (RNA), leading to protein production.
Gene expression encompasses transcription in the nucleus and translation of RNA in the cytoplasm.
There are approximately 30,000 genes per cell contributing to over 100,000 different proteins through alternative RNA processing.

Structure of DNA

DNA is composed of phosphoric acid, deoxyribose (a sugar), and four nitrogenous bases: adenine, guanine, thymine, and cytosine.
Nucleotides, formed from these components, are linked to create two strands of DNA.
Purine (adenine and guanine) and pyrimidine (thymine and cytosine) bases bond specifically: adenine pairs with thymine; guanine pairs with cytosine.

Types of RNA

Messenger RNA (mRNA) conveys the genetic code for protein formation.
Ribosomal RNA (rRNA) combines with proteins to form ribosomes, essential for protein synthesis.
Transfer RNA (tRNA) transports specific amino acids to ribosomes based on the genetic code.
MicroRNA (miRNA) regulates gene transcription and translation.

Translation Process in Protein Synthesis

mRNA enters ribosomes, where its sequence is read to link amino acids into polypeptides through peptide bonds.
Each tRNA recognizes specific mRNA codons via anticodons, ensuring the correct amino acid sequence in proteins.
The protein synthesis concludes when a stop codon appears, signaling the release of the newly formed protein.

Transport Mechanisms Across Cell Membranes

Sodium co-transport mechanisms facilitate the movement of substances like glucose and amino acids into cells alongside sodium ions.
Counter-transport involves the simultaneous movement of sodium ions into cells while transporting calcium ions or hydrogen ions out.
These processes rely on specific transport proteins that bind different substrates.

Membrane Potentials and Action Potentials

Membrane potentials arise from ionic concentration differences across cell membranes.
Potassium ions tend to diffuse outward, creating a potassium diffusion potential.
“Saltatory conduction” in myelinated fibers facilitates rapid neural impulses by allowing currents to jump across nodes of Ranvier, increasing conduction velocity by 5 to 50 times and conserving energy.

Conduction Velocity

Action potential conduction velocity varies significantly, ranging from 0.25 m/sec in small unmyelinated fibers to up to 100 m/sec in large myelinated fibers.
Conduction speed correlates with fiber diameter and myelination.

Skeletal Muscle Structure

Skeletal muscle constitutes approximately 40% of body mass, with smooth and cardiac muscles accounting for an additional 10%.
Skeletal muscle fibers extend the full length of muscles and are innervated by individual nerve endings.
Myofibrils, fundamental units within muscle fibers, comprise actin and myosin filaments, essential for muscle contraction.

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Description

This quiz covers the essential processes of protein synthesis and cellular functions, including the roles of ribosomes, the endoplasmic reticulum, and the Golgi apparatus. It also highlights the function of lysosomes and mitochondria in cellular activities. Test your knowledge on how these organelles contribute to life's processes.