Life Science Chapter 2 - Cell Structure

cell theory

The model that states that cells make up all living things, come from preexisting cells, and perform the functions of living things.

tissue

a group of similar cells that work together

organ

a group of tissues that work together

organelle

the usually membrane-surrounded structures in a eukaryotic cell that perform special functions

cell membrane

the structure that surrounds all cells and regulates what comes in and goes out

cell wall

a rigid structure which surrounds and protects some cells

capsule

a slimy layer surrounding some bacteria that protects them from harmful substances and prevents them from drying out

cytoplasm

the material inside of the cell, excluding the nucleus

flagellum

a whip-like structure that some cells use to propel themselves through their environment

DNA

the molecule that contains important information for making proteins and helps regulate many cellular processes

chromosome

a structure that contains a cell’s DNA

endoplasmic reticulum

a network of tubes in eukaryotic cells that help produce and transport proteins and other molecules throughout the cell

Golgi apparatus

the organelle in eukaryotic cells that modifies many proteins and packages them into small structures called vesicles

ribosome

a small structure that assembles proteins found in both prokaryotic and eukaryotic cells

cytoskeleton

several types of long, thin fibers anchored to various parts of the cell that help the cell maintain and change its shape

lysosome

a small organelle in eukaryotic cells that acts as the demolition crew within a cell, they destroy foreign substances such as bacteria or viruses

enzyme

a protein that speeds up or slows down chemical reactions

mitochondria

the organelle in eukaryotic cells that makes most of the cell’s ATP (the “powerhouse” of the cell)

selectively permeable

allowing some substances to pass through while keeping others out

concentration gradient

the difference in the number of a certain type of molecule on each side of a membrane

diffusion

the movement of molecules through a membrane as a result of a concentration gradient

osmosis

the movement of water across a membrane

passive transport

the movement of molecules across a membrane without the cell doing any work, as in diffusion and osmosis

active transport

the movement of molecules across a membrane that requires the cell to do work

producer

an organism that can make its own food, typically through photosynthesis

photosynthesis

the process by which a plant uses energy from the sun to turn carbon dioxide and water into the sugar glucose (and the by-product oxygen)

chlorophyll

the green pigment that absorbs sunlight for photosynthesis

ATP

the molecule that a cell uses to power many processes in the cell that need chemical energy

cellular respiration

the process of breaking down molecules to produce ATP

anaerobic

describes a process that does not use oxygen

stem cell

a special cell and divides and matures into any type of cell needed by the body