Chapter 3: Cell Metabolism and Cellular Respiration

Comprehensive practice flashcards covering Chapter 3: Cell Metabolism and Cellular Respiration, including catabolism, anabolism, organic and inorganic nutrients, and anaerobic vs. aerobic pathways.

What is metabolism?

Metabolism is the total of all the chemical reactions that happen inside cells to keep an organism alive.

Where do metabolic reactions take place?

Inside cells.

What is the primary purpose of metabolism in an organism?

To keep the organism alive.

What are the two main types of metabolism?

Catabolism and anabolism.

What does catabolism do to large molecules?

It breaks down large molecules into smaller molecules.

Does catabolism release or require energy?

Catabolism releases energy.

What is an everyday example of catabolism given in the text?

Digestion breaking large food molecules into smaller molecules.

What general equation represents catabolism?

$$\text{Large molecules} \rightarrow \text{Smaller molecules} + \text{Energy}$$

What does anabolism do to small molecules?

It builds up small molecules into larger molecules.

Does anabolism release or require energy?

Anabolism requires and uses energy.

What is an example of an anabolic process given in the text?

Protein synthesis building proteins from smaller amino acids.

What general equation represents anabolism?

$$\text{Small molecules} + \text{Energy} \rightarrow \text{Large molecules}$$

What is the definition of a nutrient?

A nutrient is a substance in food that the body needs for growth, repair, maintaining the body, and metabolism.

What four purposes does the body need nutrients for?

Growth, repair, maintaining the body, and metabolism.

How many groups of nutrients are there?

$6$ groups.

Which six groups make up the nutrients?

Water, carbohydrates, lipids, proteins, minerals, and vitamins.

What is an organic compound?

A molecule that contains carbon, usually arranged in a carbon chain.

What elements do organic compounds typically contain besides carbon?

Hydrogen, oxygen, nitrogen, sulphur, and phosphorus.

What are the four major classes of organic compounds mentioned?

Carbohydrates, lipids, proteins, and nucleic acids.

What are carbohydrates used for primarily by cells?

They are the main source of energy for cells.

Which three elements are always present in carbohydrates?

Carbon, hydrogen, and oxygen.

What is the typical ratio of hydrogen to oxygen atoms in carbohydrates?

There are generally twice as many hydrogen atoms as oxygen atoms ($2:1$ ratio).

What chemical formula is listed for glucose in the notes?

$C_6H_{12}O_6$ (noted as $C_6H_{12}C_0$ on Page 1).

What are monosaccharides?

Single sugar molecules.

What are three examples of monosaccharides?

Glucose, fructose, and galactose.

Why is glucose particularly important for cells?

Because it is used in cellular respiration to release energy.

What is a disaccharide?

A sugar consisting of two monosaccharides joined together.

What are three examples of disaccharides?

Sucrose, maltose, and lactose.

What are polysaccharides?

Carbohydrates made from many monosaccharides joined together.

What are three examples of polysaccharides?

Starch, glycogen, and cellulose.

Into what can complex carbohydrates such as starch be broken down?

Simple sugars.

What substances are included in lipids?

Fats and oils.

What function do lipids serve regarding energy?

They are an important source of energy.

Into what two components can lipids be broken down?

Glycerol and fatty acids.

What is the most common type of stored fat in the human body?

A triglyceride.

What are the chemical components of a single triglyceride?

$1$ glycerol molecule and $3$ fatty acid molecules.

What are phospholipids?

Lipids that are important components of cell membranes.

What are steroids, and what examples are given?

A type of lipid that includes cholesterol and sex hormones.

How can glycerol contribute to energy production during cellular respiration?

It can enter the glycolysis pathway.

What building blocks make up proteins?

Amino acids.

Which four elements do proteins always contain?

Carbon, hydrogen, oxygen, and nitrogen.

Which two additional elements can proteins also contain?

Sulphur and phosphorus.

Approximately how many different amino acids are used to make proteins?

Approximately $20$ different amino acids.

What are four specific examples of amino acids listed in the text?

Glycine, alanine, valine, and glutamic acid.

What bond forms when two amino acids join together?

A peptide bond.

What is a dipeptide?

A molecule consisting of two amino acids joined together by a peptide bond.

What is a polypeptide?

A chain of more than $10$ amino acids joined together.

Generally, how many amino acids make up a protein?

$100$ or more amino acids.

What determines how a protein folds into its specific shape?

The order (sequence) of amino acids.

What is one of the most important functional groups of proteins in the body?

Enzymes.

Why are enzymes critical to metabolism?

Enzymes control chemical reactions in the body.

Under what condition are proteins used as an energy source?

Usually only when carbohydrates and lipids are insufficient.

How many structural levels describe protein architecture?

Four levels.

What is the primary structure of a protein?

The amino acid sequence.

What constitutes the secondary structure of a protein?

Localized structures such as alpha helices and beta sheets.

What is the tertiary structure of a protein?

The overall 3D shape of a single polypeptide chain.

What defines the quaternary structure of a protein?

Multiple protein chains combined together.

What are nucleic acids?

Very large organic molecules that store and carry genetic information.

Which elements are found in nucleic acids?

Carbon, hydrogen, oxygen, nitrogen, and phosphorus.

What are the monomer subunits of nucleic acids called?

Nucleotides.

What are the three components of a single nucleotide?

A nitrogenous base, a sugar, and a phosphate group.

What are the two main types of nucleic acids?

DNA and RNA.

What does the abbreviation DNA stand for?

Deoxyribonucleic acid.

What sugar is present in DNA nucleotides?

Deoxyribose.

How many nucleotide strands does DNA possess?

Two strands.

Where is DNA primarily located inside the cell?

Primarily in the nucleus.

What is the primary function of DNA?

It stores genetic information needed to produce proteins.

What does the abbreviation RNA stand for?

Ribonucleic acid.

What sugar is present in RNA nucleotides?

Ribose.

How many strands does an RNA molecule usually have?

One strand.

What are the main functions of RNA?

Carrying information from DNA to ribosomes and helping with protein production.

What defines an inorganic compound?

Compounds that are not based on a carbon chain.

Do inorganic compounds typically contain carbon?

Most do not contain carbon atoms, although some exceptions exist.

What is an example of a carbon-containing inorganic molecule given in the text?

Carbon dioxide ($CO_2$).

What size are inorganic compounds that happen to contain carbon?

They are usually small molecules.

What are three important groups of inorganic compounds in living systems?

Water, minerals, and vitamins.

What is water's role as a solvent in metabolism?

It is the fluid in which other cellular substances are dissolved.

Why is water important as a medium for reactions?

Some of the cell's chemical reactions occur directly in water.

Does water participate directly in metabolic reactions?

Yes, in some chemical reactions, water molecules take part directly in the reaction.

What are two enzymatic roles of minerals in metabolism?

They may be part of enzymes or function as cofactors for enzymes.

In which key energy molecule are minerals incorporated?

Adenosine triphosphate (ATP).

What is the primary role of vitamins in metabolism?

Vitamins act as coenzymes in chemical reactions.

What is cellular respiration?

The metabolic process where organic molecules taken in as food are broken down in cells to release energy.

What cell activities utilize energy released by cellular respiration?

Cell movement, uptake of materials from surroundings, and production/secretion of new chemical compounds.

How does cellular respiration differ from breathing?

Breathing is physical gas exchange, while cellular respiration is a chemical process occurring inside every cell.

Where in the body does cellular respiration occur?

In every cell in the body.

In what two forms does cellular respiration supply energy to cells?

In the form of ATP and heat.

Which four organic molecules can be respired to release energy?

Glucose, amino acids, fatty acids, and glycerol.

What is the main food material used in cellular respiration?

Glucose.

What is the word equation for the complete respiration of glucose?

$$\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon dioxide} + \text{Water} + \text{Energy}$$

What is the balanced chemical equation for cellular respiration?

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$$

How many separate reactions are involved in breaking down glucose into $CO_2$ and $H_2O$?

More than $20$ separate reactions.

What is formed at each step of cellular respiration?

An intermediate compound.

What catalyses each individual step in cellular respiration?

A different enzyme.

Why is energy released in small amounts at each step of respiration?

To allow energy to be released in a controlled way rather than all at once.

What percentage of available energy from glucose is released as heat?

About $60\%$ of the available energy.

Can cells directly use heat energy to do cellular work?

No, cells cannot use heat energy directly.

What is the physiological role of the heat released during respiration?

It keeps body temperature constant.

Why is a continuous supply of heat needed in the body?

Because heat is continually lost to the environment.

What percentage of the released energy from respiration is used to make ATP?

About $40\%$.