Chapter 3: Nutrients, Cell Structure, and Transport Across Membranes

Flashcards covering nutrients, cell structure, and transport across membranes based on lecture notes.

What are nutrients?

Substances in food that provide structural materials or energy.

What are macronutrients?

Nutrients that are required in large amounts, including water, carbohydrates, proteins, and fats.

What is dehydration?

A decrease below the body's required water level.

What is the primary function of carbohydrates in the body?

Carbohydrates are the main energy source for the body.

How do simple carbohydrates differ from complex carbohydrates in digestion?

Simple carbohydrates are single-unit sugars digested quickly, entering the bloodstream rapidly, while complex carbohydrates are composed of many subunits arranged in branching chains.

What characterizes a processed food?

Processed food undergoes extensive refinement, stripping it of nutritional value.

What is fiber and its benefits?

Fiber is composed mainly of complex carbohydrates that humans cannot digest, helping maintain healthy cholesterol levels and decreasing the risk of certain cancers.

How are excess carbohydrates stored in animals and plants?

In animals, excess carbohydrates are stored as glycogen or fat. In plants, they are stored as starch in fruit or roots.

What are proteins primarily used for in the body?

Proteins form parts of cellular structures and processes, acting as polymers of amino acids.

What are essential amino acids?

Essential amino acids are those that cannot be made in the body and must be obtained from food.

What are complete proteins?

Complete proteins contain all the essential amino acids we need, most commonly found in meat.

What are the main functions of fats in the body?

Fats are a source of stored energy, cushion and protect vital organs, and insulate the body in cold weather.

What are essential fatty acids?

Essential fatty acids, such as Omega-3 and Omega-6, cannot be made in the body and are obtained from food like fish, potentially protecting against heart disease.

How do saturated fats differ structurally from unsaturated fats?

Saturated fats have fatty acid carbons bonded to as much hydrogen as possible, lacking double bonds and being solid at room temperature. Unsaturated fats have fewer hydrogens bound to carbons, contain double bonds, resulting in kinks in their tails, and are liquid at room temperature.

What is hydrogenation?

Hydrogenation is a process that adds hydrogen atoms to solidify unsaturated fat, increasing its level of saturation.

What are trans fats and their health risks?

Trans fats are produced by incomplete hydrogenation, changing the fatty acid structure to be flat; they are not required in the diet and are associated with increased health risks such as clogged arteries, heart disease, and diabetes.

What are micronutrients?

Micronutrients are essential substances required in small amounts, not broken down by the body, and not used for energy, such as vitamins and minerals.

What is the primary function of vitamins?

Vitamins are organic substances that usually function as coenzymes, helping to speed up the body's chemical reactions.

Which vitamin can be synthesized in the body, and what is required for its synthesis?

Only vitamin D can be synthesized in the body, requiring sunlight.

What characterizes water-soluble vitamins?

Water-soluble vitamins (B and C) are not stored by the body and can be leached out by boiling.

What characterizes fat-soluble vitamins and potential risks?

Fat-soluble vitamins (A, D, E, and K) may be stored in fat, and excess accumulation can be toxic, increasing risks of certain cancers, heart disease, and death.

What are minerals, and what are some of their essential functions?

Minerals are inorganic substances that do not contain carbon, are water soluble, supplied through diet, and are essential for fluid balance, muscle contraction, conduction of nerve impulses, and building bones and teeth.

What is calcium commonly supplemented for?

Calcium is commonly supplemented for blood clotting, muscle contraction, nerve impulses, and healthy bone structure.

What are antioxidants, and how do they function?

Antioxidants are most beneficial in whole foods and prevent cell damage by free radicals, which are highly reactive molecules with an incomplete electron shell that can damage DNA, arterial linings, and cell membranes.

What are the two main components of cytoplasm?

Cytoplasm includes cytosol and organelles.

What is the primary function of the plasma membrane?

The plasma membrane encloses all cells, defines their outer boundary, isolates cell contents from the environment, serves as a barrier, and determines what materials are allowed in or out, making it semipermeable.

What is the structure of the plasma membrane?

The plasma membrane has fluid properties allowing lipids and proteins to slide laterally, and is composed of a phospholipid bilayer where hydrophilic heads are exposed to water and hydrophobic tails interact with each other.

What is the function of embedded proteins in the plasma membrane?

Embedded proteins carry out enzymatic functions, serve as receptors for outside substances, and help transport substances throughout the cell.

What is the primary function of the cell wall?

The cell wall provides protection outside the plasma membrane and structural support for plants, fungi, and bacteria.

What does the nucleus hold in eukaryotic cells?

The nucleus holds chromatin (DNA and proteins) in eukaryotic cells and is surrounded by a nuclear envelope.

What is the function of the nucleolus?

The nucleolus is where ribosomes are synthesized, located inside the nucleus.

What is the function of the mitochondrion?

The mitochondrion produces energy for the cell through cellular respiration.

What is the function of the chloroplast?

The chloroplast produces sugars through photosynthesis in plant cells.

What is the function of the lysosome?

The lysosome contains digestive enzymes to recycle molecules.

What is the function of ribosomes?

Ribosomes assemble proteins and can be free-floating or attached to the ER.

What is the function of the rough endoplasmic reticulum (RER)?

The rough endoplasmic reticulum (RER) is a membrane network with ribosomes attached for protein synthesis.

What is the function of the smooth endoplasmic reticulum?

The smooth endoplasmic reticulum is involved in lipid synthesis or detoxification and lacks ribosomes.

What is the function of the Golgi apparatus?

The Golgi apparatus modifies, sorts, and packages proteins.

What are centrioles, and what do they do?

Centrioles are barrel-shaped rings composed of microtubules that anchor structures and help move chromosomes around when the animal cell divides.

What is the cytoskeleton?

The cytoskeleton is a framework of protein fibers that gives shape and structural support to cells.

What is the function of the vacuole in plant cells?

The vacuole stores water, sugars, and pigments in plant cells.

Name two structures present in plant cells but not animal cells.

Plant cells have a cell wall and chloroplasts, which animal cells do not.

Name two structures present in animal cells but not plant cells.

Animal cells have lysosomes and centrioles, which plant cells do not.

How are excess sugars stored in plants versus animals?

Excess sugars are stored as starch in plants and as glycogen or fat in animals.

How are excess proteins stored in the body?

Excess proteins are stored as fat.

What is metabolism?

Metabolism involves the breakdown (digestion) of food into nutrients for building blocks, energy production, repair, growth, and maintenance.

Why is nutrient transport across the plasma membrane crucial?

Food must be digested, and nutrients must be transported into cells, requiring them to get across the plasma membrane.

What does it mean for the lipid bilayer to be 'semipermeable'?

A semipermeable lipid bilayer means that only a few substances can pass through, allowing some molecules to cross while preventing others.

When do substances stop crossing the membrane during transport?

Substances that can cross the membrane will continue to cross until they reach equilibrium, where the concentration is equal on both sides.

Which types of substances can easily cross the lipid bilayer?

Hydrophobic substances like carbon dioxide and oxygen can pass more easily, as can smaller molecules like water.

What is passive transport?

Passive transport is a type of membrane transport that does not require energy.

What are the three main types of passive transport discussed?

The three main types of passive transport are diffusion, facilitated diffusion, and osmosis.

What is diffusion?

Diffusion is the movement of molecules from high concentration to low concentration until equilibrium is reached, and it does not use energy.

How does facilitated diffusion work?

Facilitated diffusion transports molecules that cannot pass the plasma membrane (hydrophilic and charged) using a protein, making it easier for them to cross the membrane without using energy, based on the concentration gradient (from high to low).

What is osmosis?

Osmosis is the movement of water across a membrane from a high concentration to a low concentration, which does not use energy and is a form of passive transport.

What is active transport?

Active transport uses proteins to transport molecules against the concentration gradient (from low to high concentration) and requires energy, typically in the form of ATP.

What is endocytosis?

Endocytosis occurs when a substance is brought into the cell by a vesicle pinching the plasma membrane inward, typically used when molecules being transported are too big for a protein.

What is exocytosis?

Exocytosis occurs when a substance is carried by a vesicle to the membrane, where the vesicle fuses with the plasma membrane to release its contents outside the cell, typically used when molecules being transported are too big for a protein.

What are nutrients?

Substances in food that provide structural materials or energy.

____ are nutrients required in large amounts, including water, carbohydrates, proteins, and fats.

Macronutrients

Which of the following is the primary function of carbohydrates in the body? a) Forming parts of cellular structures b) Insulating the body in cold weather c) Main energy source d) Storing genetic information

c) Main energy source

What characterizes a processed food?

Processed food undergoes extensive refinement, stripping it of nutritional value.

Simple carbohydrates are single-unit sugars digested quickly, entering the bloodstream rapidly, while complex carbohydrates are composed of many subunits arranged in ____ chains.

branching

Which of the following vitamins can be synthesized in the body? a) Vitamin B b) Vitamin C c) Vitamin D d) Vitamin A

c) Vitamin D

What is the primary function of the plasma membrane?

The plasma membrane encloses all cells, defines their outer boundary, isolates cell contents from the environment, serves as a barrier, and determines what materials are allowed in or out, making it semipermeable.

The mitochondrion produces ____ for the cell through cellular respiration.

energy

Which of the following best describes passive transport? a) Requires energy to move molecules against a concentration gradient b) Moves molecules from a low concentration to a high concentration c) Does not require energy and moves molecules down a concentration gradient d) Involves the pinching inward of the plasma membrane by a vesicle

c) Does not require energy and moves molecules down a concentration gradient