HEA1091 Levels of Organisation

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Questions and Answers

What is the primary role of the nucleus within a human cell?

Protein synthesis

Waste processing

Genetic material storage and regulation (correct)

Energy production

Which process within the cell is directly responsible for ATP production?

Photosynthesis

Osmosis

Diffusion

Cellular respiration (correct)

What percentage of the human body is composed of the four key elements (C, H, O, N)?

85%

100%

75%

96% (correct)

Which of the following cell organelles is involved in processing and transporting proteins?

Golgi apparatus Signup and view all the answers

What is the function of the plasma membrane in a human cell?

Protecting cellular contents Signup and view all the answers

How does hypoxia affect cellular metabolism?

It reduces cellular respiration efficiency Signup and view all the answers

Which organelle is responsible for lipid synthesis and detoxification in the cell?

Endoplasmic reticulum Signup and view all the answers

What is the primary consequence of cellular injury?

Cellular dysfunction Signup and view all the answers

What is the primary function of the plasma membrane in a cell?

To control the entry and exit of substances Signup and view all the answers

Which organelle is responsible for the synthesis of proteins?

Ribosomes Signup and view all the answers

Which component of the cell is involved in packaging and modifying proteins?

Golgi Apparatus Signup and view all the answers

What role do lysosomes play in the cell?

Digestion and waste removal Signup and view all the answers

Which of the following options accurately describes the smooth endoplasmic reticulum?

It is involved in lipid synthesis. Signup and view all the answers

Which component helps maintain the cell's shape and support?

Cytoskeleton Signup and view all the answers

What structure is known as the powerhouse of the cell?

Mitochondria Signup and view all the answers

What is contained in the nucleolus?

Ribosomal RNA (rRNA) Signup and view all the answers

Which of the following structures is involved in the transport of materials within the cell?

Vesicles Signup and view all the answers

What do ribosomes primarily use to create proteins?

Amino acids Signup and view all the answers

What is the primary function of the sodium-potassium pump in cell membranes?

To maintain sodium and potassium concentrations across the membrane Signup and view all the answers

What characteristic of the phospholipid bilayer allows it to form a barrier to certain substances?

Hydrophilic heads face outward and hydrophobic tails face inward Signup and view all the answers

Which statement accurately describes facilitated transport?

It uses specialized protein carriers to assist certain molecules across the membrane. Signup and view all the answers

What is meant by the term 'transport maximum' in the context of cell membranes?

The limit to the amount of substance that specialized carriers can transport at once Signup and view all the answers

What role does cholesterol play in the plasma membrane?

It increases the fluidity and stability of the membrane. Signup and view all the answers

Why can water pass freely through the plasma membrane while larger molecules cannot?

The plasma membrane contains channels specifically for water. Signup and view all the answers

What distinguishes active transport from passive transport mechanisms?

Active transport requires energy input to move substances against their concentration gradient. Signup and view all the answers

What is the primary function of specialized protein carriers in cell membranes?

To bind specific substances and transport them across the membrane Signup and view all the answers

What is the primary role of mitochondria in the context of aerobic respiration?

To act as a site for ATP synthesis Signup and view all the answers

During which stage of aerobic respiration is ATP produced in the mitochondrial matrix?

Krebs cycle Signup and view all the answers

What happens to the respiration process when the body cannot supply enough oxygen during intense exercise?

The body switches to anaerobic respiration Signup and view all the answers

What is a byproduct of anaerobic respiration?

Lactic acid Signup and view all the answers

Which type of cells would you expect to have the highest number of mitochondria?

Liver cells Signup and view all the answers

What is the main advantage of aerobic respiration over anaerobic respiration?

It generates more ATP Signup and view all the answers

Where does glycolysis take place within a cell?

In the cytoplasm Signup and view all the answers

What is the role of oxygen in aerobic respiration?

It is the final electron acceptor Signup and view all the answers

What happens to pyruvate when oxygen is plentiful?

It enters the mitochondria for aerobic respiration. Signup and view all the answers

What is the first step that occurs when pyruvate enters the mitochondria?

Attachment to a coenzyme to form acetyl-CoA. Signup and view all the answers

What is produced during the conversion of pyruvate that will be used later in cellular respiration?

NADH. Signup and view all the answers

The Krebs cycle begins with the combination of acetyl-CoA and which molecule?

Oxaloacetate. Signup and view all the answers

During the Krebs cycle, what happens to citric acid as it undergoes chemical changes?

It releases energy captured by NADH and FADH2. Signup and view all the answers

Which of the following is a waste product released during the conversion of pyruvate to acetyl-CoA?

Carbon dioxide. Signup and view all the answers

What type of reaction series does the Krebs cycle represent?

Chemical reactions in the mitochondria. Signup and view all the answers

Which molecule acts as a helper in the conversion of pyruvate to acetyl-CoA?

Coenzyme A. Signup and view all the answers

Study Notes

Levels of Organisation

Human body comprises four key elements: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), constituting 96% of body composition.
The human body originates from a single cell (zygote) formed by the fusion of ovum and spermatozoon during fertilization, followed by multiple cell divisions leading to specialized cells in the developing fetus.

Cell Structure and Function

A typical human cell contains various organelles: nucleus, cytoplasm, plasma membrane, endoplasmic reticulum (both rough and smooth), lysosomes, Golgi apparatus, ribosomes, and mitochondria.
The plasma membrane protects cellular contents, regulating what enters and exits, and consists of a bilayer of phospholipids with embedded proteins, sugars, and cholesterol.

Cell Transport Mechanisms

Transport mechanisms include passive diffusion, facilitated transport, and active transport.
Small molecules like water can pass freely, while larger molecules rely on specific pores or protein carriers.
The sodium-potassium pump uses active transport to maintain ion concentrations across the membrane, crucial for cellular functions and consuming up to 30% of ATP.

Energy Production in Cells

Cellular respiration occurs in three stages: glycolysis (in the cytoplasm), Krebs cycle (in mitochondrial matrix), and electron transport chain (on mitochondrial cristae).
Glycolysis breaks down glucose into two pyruvate molecules, producing energy carriers (NADH) needed for later stages.

Aerobic vs. Anaerobic Respiration

During aerobic respiration, glucose is broken down using oxygen to produce ATP, primarily in mitochondria. This process yields high ATP but requires time and adequate oxygen supply.
In anaerobic conditions, such as intense exercise, glucose is partially broken down into lactic acid, allowing for energy production without oxygen.

The Krebs Cycle

The Krebs cycle (citric acid cycle) processes acetyl-CoA to produce energy-rich carriers (NADH, FADH2) and a small amount of ATP while releasing carbon dioxide as a waste product.
The formation of citric acid from acetyl-CoA initiates a series of reactions that gradually release energy captured by carriers.

Clinical Relevance

Understanding cellular mechanisms is crucial in pre-hospital care contexts, as energy production disruptions (e.g., due to hypoxia or shock) can severely impact cell function and overall homeostasis.

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Description

This quiz focuses on the levels of organization in human cells, emphasizing their structure and clinical significance in maintaining homeostasis. It includes topics on cell organelles such as the nucleus, mitochondria, and plasma membrane, highlighting their roles in cellular injury and repair as well as energy production. Test your knowledge on these fundamental concepts in cell biology.