Chapter 3 - Nutrients and Membrane Transport Flashcards
Nutrients
The substances in food that provide energy and structural materials
Macronutrient
Nutrients that are required in large amounts (carbohydrates, proteins, water, and fats)
Dehydration
A decrease below the body’s required water level
Complex carbohydrates
Sugars that are composed of many subunits and arranged in branching chains
Processed food
Food that has undergone extensive refinement and has been stripped of much of its nutritive value
Whole foods
Foods that have not been stripped of their nutrition by processing
Essential amino acids
Amino acids that your body cannot synthesize
Complete proteins
Foods that contain all the amino acids your body needs
Essential fatty acids
Fatty acids that cannot be synthesized by your body
Saturated fat
Type of lipid rich in hydrogen and single bonds
Unsaturated fats
Type of lipid containing many carbon-to-carbon double bonds, liquid at room temperature
Polyunsaturated
Lipid that contains many unsaturated carbons
Hydrogenation
Adding hydrogen gas under pressure to make liquid oils more solid
Trams fat
Contains unsaturated fatty acids that have been hydrogenated, which changes the fat from a liquid to a solid at room temperature
Micronutrients
Nutrients that are essential in small amounts
Coenzymes
Molecules that help enzymes
Mineral
Inorganic substances that do not contain carbon but are essential for many cell functions
Vitamins
Organic substances supplied by food that often help with enzymic functions
Antioxidants
Substances in food that prevent cells from damage caused by molecules that are generated by normal cell processes
Free radicals
Highly reactive molecules with an incomplete electron shell
Organelles
Individual structures within a cell that have specific and necessary functions
Cytosol
Watery mix inside the cell that contains salt and enzymes
Cytoplasm
Includes organelles and cytosol
Plasma membrane
defines the outer boundary of each cell, isolates the cell’s contents from the environment, and serves as a barrier that determines which nutrients are allowed into and out of the cell
Cell membrane
Encloses structures within the cell
Semipermeable
Characteristic of cell membranes that only allows some substances to cross
Phospholipid bilayer
The membrane that surrounds cells and organelles and is composed of two layers of phospholipids
Fluid mosaic
The accepted model for how membranes are structured with proteins bobbing in a sea of phospholipids, allowing the composition of the membrane to change
Cell wall
Tough but elastic structure surrounding plant and bacterial cell membrane
Nucleus
Spherical cell structure that houses DNA; found in eukaryote
Nuclear envelope
The double membrane enclosing the nucleus in eukaryotes, studded with nuclear pores that regulate traffic into and out of the nucleus
Chromatin
Structure inside the nucleus that is composed of DNA and proteins
Nucleolus
Structure inside the nucleus where ribosomes are synthesized
Mitochondria
An energy-producing organelles surrounded by a double membrane (powerhouse of the cell)
Chloroplasts
An organelle in plants that uses the sun’s energy to convert carbon dioxide and water into sugars
Thylakoids
Flattened membranous sac located in the chloroplast stroma, stack to form grana
Chrolophyll
Pigment molecules that reflect green light
Lysosome
A membrane-enclosed sac of digestive enzymes that degrade proteins, carbohydrates, and fats
Ribosomes
Organelles in which proteins are assembled
Endoplasmic reticulum
A large network of membranes that begins at the nuclear envelope and extends into the cytoplasm of a eukaryotic cell
Golgi apparatus
A stack of membranous sacs that receive, modify, sort, and send proteins from ER vesicles
Centriole
A barrel-shaped rings composed of microtubules that anchor structures that help move chromosomes around when an animal cell divides
Cytoskeleton
A framework made of protein fibers that gives shape and structural support to cells
Central vacuole
Large fluid-filled organelles in plants that contain a variety of dissolved molecules, including sugars and pigments
Diffusion
The movement of molecules from where they are in high concentration to where they are in low concentration
Passive transport
When substances diffuse across the plasma membrane without requiring any energy input
Facilitated diffusion
When molecules are transported across membranes by proteins embedded in the lipid bilayer without the input of energy
Osmosis
The movement of water across a membrane (sometimes through aquaporins) from areas of high concentration to low
Active transport
The transport that uses proteins, powered by ATP, to move substances up a concentration gradient
Exocytosis
When a membrane-bound vesicle, carrying some substance, fuses with the plasma membrane and releases its contents into the exterior of the cell
Endocytosis
When a substance is brought into the cell by a vesicle engulfing and pinching the plasma membrane inward
