AP Biology Chapter 4 & 5a Flashcards

70 terms by hlrbiology 

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basal body

A eukaryotic cell organelle consisting of microtubule triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole.

cell theory

The theory that all living things are composed of cells and that all cells come from other cells.

cell wall

A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape.

cellular metabolism

The chemical activities of cells.

central vacuole

A membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development.

centriole

A structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9 and 0 pattern; involved in animal cell division.

chloroplast

An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic molecules (sugars) from carbon dioxide and water.

chromatin

The complex of DNA and proteins that constitutes eukaryotic chromosomes.

chromosome

A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell.

cilia

A short cellular appendage specialized for locomotion formed from a core of nine outer doublet microtubules and two single microtubules covered by the cell's plasma membrane.

cristae

Infolding of the inner membrane of a mitochondrion in which is embedded the electron transport chain and the enzyme catalyzing the synthesis of ATP.

cytoplasm

Everything inside a cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles.

cytoskeleton

A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.

electron microscope

An instrument that focuses an electron beam through, or onto the surface of, a specimen; achieves a hundredfold greater resolution than a light microscope.

endomembrane system

A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

endoplasmic reticulum

An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

endosymbiosis

A process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger cells.

eukaryotic cell

A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of these types of cells.

extracellular matrix

A substance in which the cells of an animal tissue are embedded; consists of protein and polysaccharides.

flagellum

A long cellular appendage specialized for locomotion. The appendages of prokaryotes and eukaryotes differ in both structure and function. In eukaryotes, they have a 9 + 2 arrangement of microtubules covered by the cell's plasma membrane.

glycoprotein

A macromolecule consisting of one or more polypeptides linked to short chains of sugars (carbohydrates).

Golgi apparatus

An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.

granum

A stack of hollow disks formed of thylakoid membrane in a chloroplast; sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.

integrin

A transmembrane protein that interconnects the extracellular matrix and the cytoskeleton.

intermediate filament

An intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells; ropelike, made of fibrous proteins.

intermembrane space

One of the two fluid-filled internal compartments of the mitochondrion. The intermembrane space is the narrow region between the inner and outer membranes.

light microscope

An optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer's eye or onto photographic film.

lysosome

A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest the cell's food and wastes.

microfilament

The thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin.

micrograph

A photograph taken through a microscope.

microtubule

The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubulins; form the basis of the structure and movement of cilia and flagella.

mitochondrial matrix

The fluid contained within the inner membrane of a mitochondrion.

mitochondrion

An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cell's ATP is made.

nuclear envelope

A double membrane, perforated with pores, which encloses the nucleus and separates it from the rest of the eukaryotic cell.

nucleoid

A dense region of DNA in a prokaryotic cell.

nucleolus

A structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits.

nucleus

The genetic control center of a eukaryotic cell.

organelle

A membrane-enclosed structure with a specialized function within a cell.

peroxisome

An organelle containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide.

plasma membrane

The membrane that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesterol.

plasmodesma

An open channel in a plant cell wall through which strands of cytoplasm connect from adjacent cells.

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

ribosome

A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. The subunits are constructed in the nucleolus.

rough ER

A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins.

scanning electron microscope

A microscope that uses an electron beam to study the surface architecture of a cell or other specimen.

smooth ER

A network of interconnected membranous tubules in a eukaryotic cell's cytoplasm; lacks ribosomes.

stroma

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water; Sugars are made in this area by the enzymes of the Calvin cycle.

thylakoid

One of a number of disk-shaped membranous sacs inside a chloroplast; contain chlorophyll and the enzymes of the light reactions of photosynthesis; A stack of these sacs are called a granum.

transmission electron microscope

A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens.

transport vesicle

A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell; buds from the endoplasmic reticulum or Golgi and eventually fuses with another membranous organelle or the plasma membrane, releasing its contents.

vacuole

A membrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell, having diverse functions (such as food storage).

active transport

The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input of energy (often as ATP).

aquaporin

A transport protein in the plasma membrane of some plant or animal cells that facilitates the diffusion of water across the membrane (through osmosis).

concentration gradient

An increase or decrease in the density of a chemical substance in an area; substances tend to move from where they are more concentrated to where they are less concentrated.

diffusion

The spontaneous tendency of a substance to move down its concentration gradient from where it is more concentrated to where it is less concentrated.

endocytosis

Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane.

exocytosis

The movement of materials out of the cytoplasm of a cell by the fusion of vesicles with the plasma membrane.

facilitated diffusion

The passage of a substance through a specific transport protein across a biological membrane down its concentration gradient.

fluid mosaic

A description of membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules.

hypertonic solution

In comparing two solutions, the one with the greater concentration of solutes; cells in such a solution will lose water to their surroundings.

hypotonic solution

In comparing two solutions, the one with the lower concentration of solutes; cells in such a solution will take up water from their surroundings.

isotonic solution

A solution having the same solute concentration as another solution, thus having no effect on passage of water in or out of the cell.

osmoregulation

Method by which organisms regulate solute concentrations and balance the gain and loss of water.

osmosis

The diffusion of water across a selectively permeable membrane.

passive transport

The diffusion of a substance across a biological membrane, without any input of energy.

phagocytosis

Cellular "eating"; a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm.

pinocytosis

Cellular "drinking"; a type of endocytosis in which the cell takes fluid and dissolved solutes into small membranous vesicles.

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles. The vesicles contain proteins with receptor sites specific to the molecules being taken in.

selective permeability

A property of biological membranes that allows some substances to cross more easily than others and blocks the passage of other substances altogether.

tonicity

The ability of a solution surrounding a cell to cause that cell to gain or lose water.

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