Science Test Review [Introduction to Cells] (1 & 2)

Vocabulary

1. cell - the basic unit of structure and function in living things
2. microscope - an instrument that makes small objects look larger
3. cell theory - a widely accepted explanation of the relationship between cells and living things
4. cell wall - a rigid supporting layer that surrounds the cells of plants and some other organisms
5. cell membrane - a thin, flexible barrier that surrounds a cell and controls which substances pass into and out of a cell
6. nucleus - in cells, a large oval organelle that contains the cell's genetic material in the form of DNA and controls many of the cell's activities
7. organelle - a tiny cell structure that carries out a specific function within the cell
8. ribosome - a small grain-shaped organelle in the cytoplasm of a cell that produces proteins
9. cytoplasm - the thick fluid region of a cell located inside the cell membrane (in prokaryotes) or between the cell membrane and the nucleus (in eukaryotes)
10. mitochondria - rod-shaped organelles that convert energy in food molecules to energy the cells can use to carry out its functions
11. endoplasmic reticulum - an organelle that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another
12. Golgi apparatus - an organelle in a cell that receives proteins and other newly formed materials from the endoplasmic reticulum, packages them, and distributes them to other parts of the cell
13. vacuole - a sac-like organelle that stores water, food, and other materials 
14. chloroplast - an organelle in the cells of plants and some other organisms that capture energy from sunlight and changes it to an an energy form that cells can use in making food
15. lysosome - a cell organelle which contains chemicals that break down large food particles into smaller ones and that can be used by the rest of the cell
16. multicellular - consisting of many cells
17. unicellular - made of a single cell
18. tissue - a group of similar cells that perform a specific function
19. organ - a body structure that is composed of different kinds of tissues that work together
20. organ system - a group of organs that work together to perform a major function

Cells and Function

• An organism's functions are the processes that enable it to live, grow, and reproduce.
• Those functions include:
• obtaining oxygen
• water
• food
• getting rid of wastes
• Cells are involved in all these functions. Cells must carry out many if the same functions as the entire organism.
• Your body's cells work together, keeping you alive,

Cell Theory

• The cell theory is a statement that explains what cells are and where they come from. It is a widely accepted explanation of the relationship between cells and living things.
• All living things are composed of cells
• Cells are the basic units of structure and function in living things
• All cells are produces from other cells
• Nobody knew cells existed until the 1600s. 
• English scientist Robert Hooke built his own microscopes and made drawings of what he saw when he looked at dead bark from certain trees,he never knew the importance of what he saw, he had seen dead cells.
• In 1838 Matthias Schleiden concluded that all plants are made of cells; a year later Theodor Schwann reached the same conclusion with animals.
• In 1855 Rudolph Virchow proposed that all new cells are formed only from cells that already exist "all cells come from cells"

Microscopes

• The microscope was very important for creating the cell theory; the first microscope was invented around 1590.
• Some microscopes focus light through lenses to produce a magnified image, others use beams of electrons.
• There are two crucial elements for every microscope:
• magnification (most) - the condition of things appearing larger than they are
• resolution - how clear the visibility is
• A magnifying glass consists of a convex lens.
• The compound microscope is the most common microscope; this type of microscope magnifies with two lenses at once;
• one lens is fixed in the eyepiece (x10)
• second lens is chosen from a group of two or three lenses on the revolving nosepiece, each lens has a different magnifying power (4x, 10x, 40x, 100x)
• The microscopes used by Hooke, Leeuwenhoek, and other early researchers were all light microscopes.
• Since the 1930s, scientists have developed several types of electron microscopes. These use a beam of electrons instead of light to produce a magnified image. These microscopes can obtain pictures of objects that are too small to be seen with compound-light microscopes.
• electrons - tiny particles that are smaller than atoms
• Electron microscopes allow higher magnification and better resolution than light microscopes.

Animal Cell

1. Cell membrane - Outer barrier of the cell whose task is to control the movement of substances into and out of the cell. It is also known as a phospholipid membrane.
2. Cytoplasm - Substance that supports all of the cell's organelles. It has a network of microtubules and microfilaments.
3. Nuclear membrane - Surrounds the nucleus and has pores through which the materials may go in or out of the nucleus.
4. Nucleus - Most important cell structure because it controls all of the cell's processes. The nucleus has a cell's genetic code, genetic material (chromosomes and genes). It is the DNA's responsibility to control the cell's activities.
5. Nucleolus - Dense area in the nucleus whose task is to make ribosomes.
6. ER (endoplasmic reticulum) - Network of tubes that move materials within the cell, There are two types of ER: rough ER and smooth ER. Rough ER has ribosomes attached to it.
7. Ribosomes - They are the sites for protein synthesis. Some are attached to the ER, others are on the cytoplasm.
8. Mitochondria - Also known as the powerhouse of the cell because of the energy (ATP) produced by a process known as cell respiration.
9. Lysosomes - They "digest"and remove the unwanted materials in the cell. Plant cells do not have lysosomes.
10. Vacuoles - They have many different tasks such as: enclosing and releasing waste products from the cell. Plant cells have a single large vacuole, animal cells have many smaller ones.
11. Golgi Body - It packages and exports substances and complex materials from the cells. Alas, lysosomes are made in the Golgi body.

Plant Cell

1. Cell membrane - Outer barrier of the cell whose task is to control the movement of substances into and out of the cell. It is also known as a phospholipid membrane.
2. Cytoplasm - Substance that supports all of the cell's organelles. It has a network of microtubules and microfilaments.
3. Nuclear membrane - Surrounds the nucleus and has pores through which the materials may go in or out of the nucleus.
4. Nucleus - Most important cell structure because it controls all of the cell's processes. The nucleus has a cell's genetic code, genetic material (chromosomes and genes). It is the DNA's responsibility to control the cell's activities.
5. Nucleolus - Dense area in the nucleus whose task is to make ribosomes.
6. ER (endoplasmic reticulum) - Network of tubes that move materials within the cell, There are two types of ER: rough ER and smooth ER. Rough ER has ribosomes attached to it.
7. Ribosomes - They are the sites for protein synthesis. Some are attached to the ER, others are on the cytoplasm.
8. Mitochondria - Also known as the powerhouse of the cell because of the energy (ATP) produced by a process known as cell respiration.
9. Vacuole - They have many different tasks such as: enclosing and releasing waste products from the cell. Plant cells have a single large vacuole, animal cells have many smaller ones.
10. Golgi Apparatus - It packages and exports substances and complex materials from the cells.
11. Cell wall - Rigid outer boundary that surrounds the cell membrane. It has a strong material called cellulose.
12. Chloroplasts - Chlorophyll filled structures where photosynthesis occurs.

Cells in Organisms

• Organisms with many cells are called multicellular, plants and animals are multicellular organisms. Cells often look different in an organism, they perform different functions.
• Organisms that consist of one cell, or are single-celled, are called unicellular.
• All cells in a multicellular organisms must carry out key functions such as:
• getting oxygen
• This can be called a "division of labor", as all the cells execute different tasks, but for a common purpose.
• cell - basic building block of all organisms
• tissue - group of similar cells that work together to perform a function
• organ - different kinds of tissues working together to perform a function
• organ system - group of organs that work for a major function
• organism - a living thing hing, may be unicellular or multicellular