Biology Unit 3

nucleus

a cell structure that contains DNA and controls the functions of the cell

eukaryotic cell

a cell that has a nucleus, multiple chromosomes, and membrane-bound organelles

prokaryotic cell

a cell that lacks a nucleus and membrane-bound organelles

Krebs cycle

a cyclical set of reactions in which pyruvic acid is metabolized and ATP, NADH, and FADH2 are formed

organelle

a differentiated structure within a cell, such as a mitochondrion, vacuole, or chloroplast, that performs a specific function

tissue

a group of cells that are similar in structure and that work together to perform a certain function

organ

a group of different tissues that work together to perform a specific function

thylakoid

a membrane in the chloroplast that contains proteins used in the formation of ATP

carrier protein

a membrane transport protein that allows molecules to cross passively to the other side of the membrane

central vacuole

a membrane-bound compartment in a plant cell that helps regulate the water content of the cell, store waste material, and support the cell through internal pressure

Golgi body

a membranous organelle of a eukaryotic cell, which manufactures or modifies, packages, sorts, and transports molecules of the cell

chlorophyll

a molecule in plants that plays a key role in photosynthesis

glucose

a monosaccharide with the chemical formula C6H12O6used by cells for energy

endoplasmic reticulum

a network of membranes in a eukaryotic cell, some with ribosomes attached, that is interconnected with the outer nuclear membrane

enzyme

a protein that is a catalyst for chemical reactions in organisms; it increases the rate of the reaction without being used up or changed

nucleolus

a region of the nucleus where ribosomal RNA (rRNA) is produced

gamete

a reproductive cell that can fuse with another to form a zygote; also known as sex cells

cell wall

a rigid structure surrounding a cell, outside the cell membrane, that gives the cell support and shape

gene

a segment of DNA that directs the development of some inherited traits

chromosome

a single long molecule of DNA wound around proteins called histones

cytoskeleton

a system of filaments and tubules made of proteins that gives the cell its overall support and structure

meiosis

a type of cell division in which the resulting cells have half the chromosome number of the parent

cytokinesis

after mitosis or meiosis, the division of a cell's cytoplasm into two separate cells

stem cells

cells of an undifferentiated type that are capable of becoming specialized

histone

certain proteins found in association with chromosomes

unicellular

composed of a single cell

multicellular

composed of many cells

cytoplasm

everything, except for the nucleus, that is contained within the cell membrane; it includes the organelles and the cytosol

meristems

localized tissues where growth occurs in a plant

lysosomes

membrane-bound organelles, usually spherical, that contain enzymes to break down molecules in eukaryotic cells

spindle fibers

microtubules that extend from the centromeres to each chromosome during mitosis and meiosis at metaphase, along which the chromosomes separate during anaphase

electron carrier

molecules such as FADH2 and NADH that carry electrons from one part of a chemical process to another

passive transport

movement of materials across a membrane that does not require energy from the cell

anaerobic

not using oxygen; when applied to organisms, cells, or tissues, it means they do not use oxygen as part of the process of obtaining energy from glucose

Archaea

one of the three domains of life, made up of prokaryotic organisms, most of which live under extreme conditions of temperature or in harsh chemical environments and differ in basic ways from the other main group of prokaryotic organisms, Bacteria

chromatid

one of the two identical strands of a chromosome

mitochondria

organelles that are the sites of cellular respiration

semipermeable

permeable to some molecules, but not to others

diffusion

process in which atoms and molecules move from an area where they are more concentrated to an area where they are less concentrated

ribosomes

small organelles, made of RNA and protein; sites of protein synthesis

interphase

stages of growth of a cell and duplication of the DNA during the cell cycle

haploid

the 1n condition in which no chromosome is part of a homologous pair in a cell

diploid

the 2n condition in which every chromosome is part of a homologous pair in a cell

cell

the basic unit of life, of which all living things are made

fermentation

the breakdown of pyruvic acid in the absence of oxygen

zygote

the cell that results from the fusion of two gametes

resting potential

the change in polarity along a neuron that allows for transmission of an electrical impulse when a cell is not active

phospholipid bilayer

the double layer of phospholipids that makes up the membranes of a cell

crossing-over

the exchange of DNA between two homologous chromosomes during meiosis

egg

the female gamete; alternatively, (in some vertebrates) a shelled structure containing the developing embryo

glycolysis

the first stage of cellular respiration in which glucose molecules are broken down to produce pyruvic acid

stroma

the fluid part of a chloroplast that contains DNA, ribosomes, and all enzymes needed during certain stages of photosynthesis

cytosol

the fluid portion of the cytoplasm

cristae

the folds of the inner membrane of a mitochondrion

sperm

the male gamete

cell membrane

the membrane surrounding the cell; composed of a bilayer of phospholipids

ATP

the molecule that delivers usable chemical energy for almost all processes and reactions that a cell must undergo to survive

endocytosis

the movement of materials into a cell by use of a vesicle

chloroplasts

the organelles responsible for capturing light energy in photosynthetic organisms; contain chlorophyll

food chain

the pathway along which food is transferred from one organism to another

centromere

the point in a chromosome at which two chromatids are joined

asexual reproduction

the process by which an organism produces a new, genetically identical organism without the use of gametes

sexual reproduction

the process by which organisms produce a new, genetically unique organism using gametes

electron transport chain

the process by which oxygen is used during the production of most of the ATP from cellular (aerobic) respiration

photosynthesis

the process by which plants and certain other organisms use the energy of sunlight to convert carbon dioxide and water into sugar and oxygen

mitosis

the process by which the nucleus of a cell divides to form two identical nuclei

cellular respiration

the process of breaking down glucose for the production of ATP in the presence of oxygen

cell differentiation

the process of cell modification from a generalized cell to one that performs a specific task

concentration gradient

the region over which there is a change in concentration of a substance

light-independent reactions

the second and final stage in photosynthesis; also called the Calvin cycle

Calvin cycle

the stage of photosynthesis in which carbon dioxide from the atmosphere is assembled into sugars; also called light-independent reactions

cell theory

the theory that states that the cell is the basic unit of life and that cells come only from existing cells

homologous chromosomes

two chromosomes of a cell that have the same general shape and the same genes, one derived from each parent

aerobic

using oxygen; when applied to organisms, cells, or tissues, it means they use oxygen as part of the process of obtaining energy from glucose

hydrophobic

water hating; not soluble in water

hydrophilic

water loving; soluble in water

aqueous

watery