unit 3: Cells

Cell

Basic unit of life

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelle

unicellular organism

An organism made up of one cell.

Multicellular organisms

Organisms composed of many cells (Ex. tissue, humans, etc.)

Eukaryotic cells

Contain a nucleus and other organelles that are bound by membranes.

domains of prokaryotes

Bacteria and Archaea

Domains of Eukaryotes

protists, fungi, animals, and plants

Organelle

specialized structure within a cell that performs important cellular functions

All eukaryotic cells have

nucleus, plasma membrane, mitochondria

unique plant organelles

cell wall, chloroplasts, large central vacuole

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Facilitated diffusion

process of diffusion in which molecules pass across the membrane through cell membrane channels

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Osmosis

Diffusion of water through a selectively permeable membrane

Hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

istonic

when the concentration of two solutions is the same

Hypotonic

Having a lower concentration of solute than another solution

Exocytosis

a process by which the contents of a vesicle are released to the exterior through fusion of the vesicle membrane with the cell membrane.

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Nucleus

the part of the cell where DNA is stored, controls activities of the cell

nuclear envelope

Double bilayer membrane perforated with pores that control the flow of materials in and out of the nucleus.

nuclear pores

holes in the nuclear envelope that allow materials to pass in and out of the nucleus

Chromatin

Substance found in eukaryotic cells that consists of DNA coiled around histones

Chromosomes

tightly wrapped DNA around histones proteins that is twisted and folded

Nucleolus

Found inside the nucleus and produces rRNA to form ribosomes

Transcription

synthesis of an RNA molecule from a DNA template

Translation

Process by which mRNA is decoded and a protein is produced

Ribosomes

site of protein synthesis

Rough Endoplasmic Reticulum

System of internal membranes within the cytoplasm. Membranes are rough due to the presence of ribosomes. functions in transport of substances such as proteins within the cytoplasm

Smooth Endoplasmic Reticulum

An endomembrane system where lipids are synthesized and toxic substances are broken down.

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

Vesicle

A membrane bound sac that contains materials involved in transport of the cell.

Lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell

Peroxisomes

Contain oxidase enzymes that help in metabolic reactions

Plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

Centrioles

Cell organelle that aids in cell division in animal cells only

Chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

Mitochondria

An organelle found in large numbers in most cells, in which the biochemical processes of respiration and occurs

Photosynthesis

Conversion of light energy from the sun into chemical energy.

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

Vacoule

a organelle that stores water, food or other substances; plant cells have a large central vacoule

Flagella

A long, whip-like filament that helps in cell motility. Many bacteria are flagellated, and sperm are flagellated.

Cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

extracellular matrix

a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells.