Cell Structure (25)

Cell Membrane

All cells have an outer covering called CELL MEMBRANE. It is a flexible barrier between the cell and the environment. Is selectively permeable, which means that it allows only certain molecules to pass through it. e.g. water can move in and out. If cells have cell walls, the cell membrane is INSIDE of it.

Cell specialization

Cells throughout an organism can develop in different ways to perform different tasks

Vacuole

Fluid-filled storage sac (large in plants, small in animals). Vacuole are used for the temporary storage of materials like water, waste, food... in plant cells the vacuole is huge and make up most of the cell's volume.

tissue

Group of similar cells that work together to do one job. Each cell in a tissue does its part to keep the cell alive. Example: cardiac muscle

Chloroplasts

IIn plant cells, food is made in green organelles named Chloroplasts. Organelle capable of photosynthesis; using light energy, this organelle combines carbon dioxide and water to form glucose (sugar). Chloroplasts contains the green pigment chlorophyll which gives the plants their green color and is used for photosynthesis.

Cell Wall

Inflexible (rigid) barrier found only in plants, algae, fungi and most bacteria. Not in animals and protozoa. It protects the cell and provides shape and structure. Also holds back pressure preventing breakage when water enters the cell.

Endoplasmic Reticulum

Organelle composed of a series of folded membranes. Acts as a transportation network for proteins and enzymes. May be "rough" or "smooth"

Nucleus

Organelle that acts as the control center (brain) for the cell and contains genetic information (DNA). The nucleus contains the instructions for everything the cell does. These instructions are found on DNA.

Mitochondria

Organelle where energy is released. The "powerhouse" of the cell. Organelle where glucose is broken down to release energy. Potential energy is stored in the form of ATP, a chemical that acts as the cell's "currency".

Ribosomes

Organelles that serve as the site for protein synthesis (where proteins are made). Proteins are needed in nearly every cell activity.

organ

Structure made up of two or more different types of tissues that work together.Example, the heart.

Nucleolus or Nucleoli

Structure(s) found inside the nucleus that produce ribosomes.

Lysosome

This organelle contains digestive enzymes used to "split" substances apart. This organelle also helps to breakdown dying and worn-out cell parts.

Cell theory

idea that: 1) all living things are composed of cells, 2) cells are the basic units of structure and function in living things 3) new cells are produced from existing cells

photosynthesis and respiration

2 processes that make energy for organisms but are opposites of each other. Plant cells use water, carbon dioxide and the suns energy to make glucose (sugar) and oxygen. Animal cells use oxygen and sugar to make energy and waste carbon dioxide and water.

Chlorophyll

A green molecule found in chloroplasts that absorbs light energy.

organ system

A group of organs working together to perfom a certain functions. Example heart + arteries + veins + capillaries = cardiovascular system

Eukaryote

An organism that possesses eukaryotic cells; Eukaryotic possess a nucleus and other membrane-bound structures. Eukaryotes include all organisms (animals, plants, fungi, and protists) except bacteria.

Prokaryote

An organism that possesses prokaryotic cells; Prokariotic cells that lack a nucleus and other membrane-bound structures. The only prokaryotes are bacteria.

mitosis and meiosis

Cells divide for two purposes, they are: to create more of the same cells or to create sex cells with genes of both parents. Mitosis makes 2 clone daughter cells. Meiosis makes 4 different daughter cells.

Golgi Body (Apparatus)

Packages, modifies, and distributes newly made substances. Activates enzymes. The "Post Office" of the cell... (Shown as the green, folded structure in the diagram)

Cell

The basic unit of life. It is the SMALLEST unit that is capable of performing life functions. Cells can be divided in two groups: Prokaryotic (non membrane) and Eukaryotic (has membrane). There are lots of sizes of cells. A human egg cell is like the dot in the i. A bacteria is about...80,000 times smaller.

Organelle

The name for a structure within a cell with a specific cell function. Some organelles process energy, move materials, storage... Nucleus is usually the largest organelle in the cell.

Cytoplasm

a jellylike fluid that fill the cell in which the organelles are supported.In the cytoplasm of every cell there is hereditary material that controls the life of the cell. Most of a cell's life processes occur in the cytoplasm.

levels of organization

atoms, molecules, organelles, cells, tissues, organs, organ systems, organism