Biology Theme 1 Module 1 Quiz

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Questions and Answers

What is the primary function of ATP in cellular processes?

To serve as a molecular fuel for cellular activities. (correct)

To transport molecules across the cell membrane.

To act as a structural component of cell membranes.

To store genetic information for protein synthesis.

What are the products of glycolysis for each glucose molecule metabolized?

2 molecules of ATP and 4 molecules of NADH.

1 molecule of ATP and 3 molecules of NADH.

2 molecules of ATP and 2 molecules of NADH. (correct)

4 molecules of ATP and 2 molecules of NADH.

Which compound is formed after pyruvate is processed following glycolysis?

Acetyl CoA. (correct)

Oxaloacetate.

Citric acid.

Lactic acid.

During the Krebs cycle, which additional products are generated along with ATP?

FADH2 and carbon dioxide. Signup and view all the answers

Why do cells evolve fast glucose processing systems?

To counteract the short supply of ATP for cellular activity. Signup and view all the answers

What is the primary function of proteins in a cell?

Perform metabolic activities and provide structural support Signup and view all the answers

Which of the following describes phospholipids in the cell membrane?

They consist of a glycerol backbone, phosphate group, and two fatty acids. Signup and view all the answers

Why are cell membranes described as thin and flexible?

Their thickness ranges from 5-10 nm, allowing for flexibility. Signup and view all the answers

What is the significance of the hydrophobic core of the lipid bilayer?

It creates a barrier against water-soluble substances. Signup and view all the answers

Which of the following best describes the properties of phospholipids?

They are amphipathic with both hydrophobic and hydrophilic regions. Signup and view all the answers

What roles do polysaccharides play in cells?

They provide structural support and energy storage. Signup and view all the answers

What kind of structure do lipid micelles form?

A spherical structure that facilitates absorption of fat-soluble substances. Signup and view all the answers

How do water molecules interact with phospholipids in the membrane?

They interact with the hydrophilic heads, allowing the tails to aggregate. Signup and view all the answers

What type of cells make up the human body?

Both eukaryotic and prokaryotic cells Signup and view all the answers

Which of the following statements about bacterial cells in the human body is true?

They can contribute essential functions to physiological systems. Signup and view all the answers

What is one primary characteristic of eukaryotic cells?

They have a nucleus containing genetic material. Signup and view all the answers

Which of the following is NOT a component of the microbiome?

Red blood cells Signup and view all the answers

How much do bacterial cells weigh in a 150-pound person?

3-4.5 pounds Signup and view all the answers

What is the primary role of Bacteroides thetaiotaomicron in the human body?

To break down plant material Signup and view all the answers

Which of the following is a common inhabitant of the upper respiratory tract?

Streptococcus salivarius Signup and view all the answers

What defines a eukaryotic cell?

Presence of membrane-bound organelles Signup and view all the answers

What type of bond is formed between the carboxyl group of one amino acid and the amino group of another during peptide formation?

Peptide bond Signup and view all the answers

What term is used to describe the individual amino acids once they are linked together in a polypeptide?

Residues Signup and view all the answers

Which property of amino acids is influenced by the R group?

Unique properties Signup and view all the answers

What is the primary fate of proteins synthesized by free ribosomes in the cytosol?

They remain in the cytosol or target organelles. Signup and view all the answers

How do hydrophobic amino acid side chains behave in aqueous environments?

They aggregate as a result of thermodynamically stable interactions. Signup and view all the answers

Which mechanism is used to direct proteins to their specific organelles?

Unique signal sequences within the protein Signup and view all the answers

What determines the three-dimensional structure of a protein after synthesis?

The interactions among side chains of amino acids Signup and view all the answers

What type of charge do polar hydrophilic side chains typically have?

Polar and possibly charged Signup and view all the answers

What property of phospholipid tails affects the overall behavior of the phospholipids in a membrane?

The length of hydrocarbon chains Signup and view all the answers

What role does cholesterol play in cellular membranes?

Decreases the overall fluidity Signup and view all the answers

How does the structure of unsaturated fatty acids affect membrane fluidity?

They introduce bends that increase fluidity Signup and view all the answers

What happens to the fluidity of a membrane at higher temperatures?

Fluidity increases Signup and view all the answers

Which of the following statements about phospholipids is true?

They can move laterally within one layer of the lipid bilayer Signup and view all the answers

What is a characteristic of steroids that differentiates them from phospholipids?

They have a 4-hydrocarbon ring structure Signup and view all the answers

Which factor does NOT affect the fluidity of membranes?

Concentration of oxygen in the membrane Signup and view all the answers

Which of these properties describes hydrocarbon chains in phospholipids?

They consist of saturated and unsaturated configurations Signup and view all the answers

Study Notes

Cells in Our Body

Humans originate from a single fertilized egg, which undergoes mitotic divisions to develop into approximately 10 trillion cells.
These cells include diverse types such as muscle, skin, kidney, and neurons, all categorized as eukaryotic due to their nucleus containing genetic material.
Key cell classifications:
- Eukaryotic cells: Plant, animal, fungi
- Prokaryotic cells: Bacterial cells
Human body harbors ten times more bacterial cells than eukaryotic cells, contributing to 2-3% of body mass (e.g., a 150-pound person may carry 3-4.5 pounds of bacteria).
Most bacteria are beneficial, performing essential functions within physiological systems; some can be harmful if they enter the body.

Microbiome

Defined as populations of microorganisms, invisible to the naked eye but observable under a microscope.
Composed of prokaryotic bacteria and small eukaryotic organisms that inhabit all parts of the body, including the skin and digestive system.
Approximately 10,000 distinct microbial species exist on and in a healthy human body.
Notable bacteria include:
- Streptococcus Aureus: Can induce skin and respiratory infections.
- Streptococcus Salivarius: Harmless in oral cavity; contributes to dental plaque formation and colonizes newborns' gastrointestinal tract.
- Staphylococcus haemolyticus: Common on skin.
- Bacteroides thetaiotaomicron: Important intestinal bacteria breaking down plant material.

Phospholipids: Building Blocks of Membranes

All cells are encased in membranes rich in phospholipids.
Definition of a cell includes macromolecules:
- Nucleic acids: Hereditary information; DNA is processed into RNA for protein synthesis.
- Proteins: Structural and functional elements including enzymes.
- Polysaccharides: Structural roles and energy sources (e.g., plant cell walls).
- Phospholipids: Key components of cell membranes, creating barriers.
Cell membranes maintain distinct internal environments, crucial for toxin control and nutrient absorption.

Structure and Function of Cell Membranes

Membranes consist of lipid macromolecules with hydrophobic cores and hydrophilic properties, forming lipid bilayers.
Phospholipids are amphipathic, possessing hydrophobic tails and hydrophilic head groups, allowing bilayer formation.
Membrane thickness ranges from 5-10 nm, thin enough that 100 layers equal the thickness of paper.
Phospholipid properties:
- Tails consist of saturated (single bonds) or unsaturated (double bonds) hydrocarbons, affecting fluidity and permeability.

Membrane Fluidity Factors

Fatty Acid Tail Length: Longer chains pack tightly, reducing membrane fluidity.
Saturation: Double bonds create bends in tails, increasing fluidity by spacing out phospholipids.
Temperature: Higher temperatures enhance fluidity; cold-adapted organisms have more unsaturated phospholipids to maintain fluidity under lower temperatures.
Cholesterol: Integral in membranes, making up 50% of lipid molecules; moderates membrane fluidity by restricting phospholipid movement.

Cellular Energy and Metabolism

ATP serves as the molecular fuel for cellular activities, generated primarily through cellular respiration from glucose.
Glycolysis occurs in the cytosol, producing 2 ATP and 2 NADH, followed by pyruvate processing leading to the Krebs cycle in mitochondria.

Protein Synthesis and Folding

Translation of mRNA to polypeptide involves amino acids linking through peptide bonds, forming polypeptides characterized by R groups that define properties.
Proteins reaching functional shapes rely on interactions of R groups, leading to established three-dimensional structures.
Ribosome location influences protein destination:
- Free ribosomes produce cytosolic proteins or those targeting organelles.
- Special sequences within proteins guide them to specific organelles.

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Description

Test your understanding of the composition and structure of membranes in biological cells. This quiz covers the fundamental aspects of cell division and the differences among various eukaryotic cells in the human body. Challenge yourself with questions on cell types, functions, and the importance of membranes.