Grade 6 Science: Cells and Cell Structure

Vocabulary flashcards covering cell theory, basic cell substances, macromolecules, prokaryotic versus eukaryotic cells, and the organelles of plant and animal cells.

Cell Theory

States:

All living things are made up of one or more cells.

The cell is the basic (smallest) unit of life.

All new cells come from preexisting (old) cells.

Basic Cell Substances

Water:

The main ingredient in a cell.

Makes up $70\%$ of a cell's volume.

Water also surrounds cells and helps insulate the human body.

Macromolecules

A substance in cells that forms when many small molecules join together.

Nucleic Acid

Are macromolecules that form when long chains of molecules called nucleotides join together.

Contains genetic information (DNA).

The order of nucleotides is important because it encodes the genetic information.

Proteins

Are long chains of amino acid molecules.

Each protein can have different functions, including communication, transportation, breaking down food, and support.

Lipids

Large macromolecules that do not dissolve in water.

They act as protective barriers in the cell membrane.

They store energy, and aid in cell communication.

Carbohydrates

A Macromolecule made of 1 or more sugar molecules, which are composed of Carbon, Hydrogen, and Oxygen, usually the body’s major source of energy.

They store energy, provide structural support, and are needed for communication between cells.

Carbohydrates can be found in sugars and starches.

Cellulose is a carbohydrate found in plants.

Cellulose

A carbohydrate found in plants that provides structural support.

Cell Shape and Movement

The size and shape of a cell can relate to its function.

Blood cells are small and disk shaped, nerve cells can be stretched out to reach long distances through the body.

Cell Membrane

A flexible, semi-permeable covering mostly made of proteins and phospholipids that separates internal cell parts from the outside environment and controls what enters and exits the cell.

Cell Wall

A stiff, rigid outer layer outside the cell membrane in plant cells that protects the cell from viruses and harmful organisms, maintains its shape, and provides structural support.

Cytoplasm

A gel-like fluid inside a cell between the cell membrane and nucleus that contains salts and other molecules and keeps all organelles suspended in place.

Prokaryotic Cells

Unicellular organisms that do not have many cell parts and whose DNA is spread out like a plate of spaghetti rather than enclosed in a nucleus.

Eukaryotic Cells

Complex, organized organisms that have organelles with specialized functions and genetic material (DNA) surrounded by a membrane known as the nucleus.

Nucleus

The largest organelle inside most eukaryotic cells, known as the control center, which contains genetic information (DNA) and directs all cell activities.

Nucleolus

A round structure inside the nucleus that produces and assembles ribosomes.

Ribosomes

Tiny round structures that make proteins; they can float freely in the cytoplasm or be attached to the endoplasmic reticulum.

Endoplasmic Reticulum

A network of passageways that transports proteins and other substances around the cell.

Golgi Body

An organelle (also known as the Golgi apparatus) that sorts, packages, and distributes proteins and other materials to different parts of the cell.

Lysosome

An organelle containing enzymes that break down worn-out organelles and rid the cell of waste.

Mitochondria

Known as the powerhouse of the cell, these organelles produce most of the cell's energy (singular: mitochondrion).

Vacuole

A cell storage unit that stores materials such as food, water, or waste.

Chloroplast

A membrane-bound organelle found in plant cells that captures sunlight and converts light energy into food through photosynthesis.

Large Central Vacuole

An extra-large organelle found in most plant cells that stores water, food, and waste.