BIO 2 GO!
3216a
The Cell - Nucleus
The cell is the smallest unit of life. Each living cell has a nucleus
which functions to control the actions of the rest of the cell.
The Cell - Nucleus
3.2.1.6a
Upon successful completion of this unit, you should be able to do the following:
1. Explain and describe the structure and function of a cell and the nucleus of
a cell.
2. Explain and describe the role of DNA in the nucleus.
3. List and describe the function of 10 cellular organelles.
4. Be able to use the following words in their correct context:
Cell
Nucleus
DNA
RNA
Ribosome
Chloroplast
Mitochondrion
Cell wall
Cell membrane
Lysosomes
Golgi Complex
Vacuole
Endoplasmic reticulum
Organelle
The Cell - Nucleus
3.2.1.6a
The smallest and simplest basic unit of life is the cell. A cell is a membranecovered structure that contains all of the materials needed for life. Every
living thing, both plant and animal, is made of cells. There are similarities in all
animal cells and similarities in all plant cells. In fact, there are even similarities
between plant and animal cells!
Most cells contain a nucleus.
The nucleus is a membrane-covered organelle that serves 2 functions:
1) The nucleus contains the cell’s DNA and
2) The nucleus serves as a control center for the cell.
1. DNA
As you recall, DNA is the code, or blueprint for making a new organism. Every
cell with a nucleus contains DNA in the nucleus. Whenever a cell wants to
reproduce, it must make new DNA for the offspring.
2. Control Center
The nucleus of the cell tells the rest of the cell what to do. The nucleus is
the “brains” of the cell. The nucleus is in charge of all of the cell’s functions. If
something happens to the nucleus, the cell dies.
REMEMBER THIS!!!
All living things are made of cells. Each cell contains a nucleus that
controls the activities of the cell and stores the DNA for the cell.
Interesting Scientific Fact: Not all cells look alike. Those cells with a similar
function usually look alike. Those cells with a different function do not look alike.
All skin cells tend to look the same. However, a skin cell is different from a muscle
cell. The longest cells in the human body are nerve cells. Nerve cells can be more
than 1 meter long!
Question 1. Explain what you know about cells.
Student’s answers will vary.
Question 2. What are the 2 functions for the nucleus?
Holds the DNA and is the control center of the cell.
Question 3. Where is the nucleus located?
Near the middle of the cell.
Cellular Organelles
A cellular organelle is a special structure located in a cell. The following
organelles are found in almost every cell. They are under the control of the
nucleus. They each contribute to the well being of the cell. It is important that
you are able to list and explain the function of each of these cellular organelles.
1. nucleus – contains the cell’s DNA and is the control center of the cell
2. ribosomes – the site where amino acids are hooked together to make
proteins
3. endoplasmic reticulum – makes lipids and packages protein for use outside of
the cell.
4. mitochondria – the site where food molecules are broken down to make ATP
(energy).
5. chloroplasts – found in green plants only; the site where food is made for
the plant by using the energy of sunlight (photosynthesis occurs here).
6. Golgi complex – packages and transports materials out of the cell
7. vacuole – a bag-like structure that stores water for the cell to use
8. lysosomes – are structures that digest wastes, foreign invaders, and
broken cell parts.
9. cell wall – found in plants only; rigid structure that surrounds and provides
support for each plant cell
10. cell membrane – a phospholipids layer that surrounds every cell and acts as
a barrier between the inside and outside of a cell.
Summary
The Cell and Nucleus
3216 a
The cell is the basic unit of life. Some organisms are made of only one cell
(unicellular), while others are made of billions of cells (multicellular). Organisms
are very different yet the cells they are made of are very similar.
A cell’s job is to make molecules and to eventually reproduce itself. The cell
makes molecules for its own use, or to be used elsewhere outside of the cell. The
cells make proteins, lipids, carbohydrates, and nucleic acids.
Most cells have a nucleus. In the nucleus is DNA, a material that holds the
genetic code for all of the proteins that the cell needs to make. The nucleus is
surrounded by a nuclear membrane. It has large pores to let RNA in and out, but
DNA is so large, it cannot get out of the nucleus.
TEST YOURSELF
Matching
__D__ 1. cell
a. joins amino acids to make a protein
__E__ 2. nucleus
b. organelle that can carry out
photosynthesis
__F__ 3. DNA
c. organelle that can carry out cellular
respiration
__A__ 4. ribosome
d. the basic unit of life
__B__ 5. chloroplast
e. store DNA
__C__ 6. mitochondrion
f. a molecule that holds the code for all of
the proteins that a cell needs to make
__H__ 7. cell wall
g. structure that digests waste, foreign
invaders
__G__ 8. lysosomes
h. hard covering that surrounds plant cells
__J__ 9. Golgi complex
i. bag-like structure that holds water in the
cell
__I__ 10. vacuole
j. organelle that packages and transports
materials out of the cell.
__K__ 11. endoplasmic reticulum
k. makes lipids and packages protein for use
outside of the cell.
__L__ 12. cell membrane
l. protective covering surrounding all cells
True or False
__T__ 1. Some organisms are made of only one cell.
__T__ 2. Some organisms are made of billions of cells.
__F__ 3. The cells in different organisms are very different.
__T__ 4. The cells in different organisms are very similar.
__F__ 5. The nucleus can make glucose using the light from the sun.
__F__ 6. The nucleus can join amino acids to make a protein.
__T__ 7. The nucleus stores DNA.
__T__ 8. The nucleus stores molecules that hold the code for all of the proteins
that a cell needs to make.
__F__ 9. The ribosomes can make glucose using the light from the sun.
__T__ 10. The ribosomes can join amino acids to make a protein.
__T__ 11. The chloroplasts can make glucose using the light from the sun.
__F__ 12. The chloroplasts can join amino acids to make a protein.
__F__ 13. The mitochondria can make glucose.
__T__ 14. The mitochondria can break apart glucose.
__F__ 15. A cell only needs its nucleus to be able to make its proteins.
__F__ 16. The endoplasmic reticulum makes DNA
__T__ 17. Lysosomes protect the cell by digesting unwanted substances.
__F__ 18. Lysosomes digest DNA and cell wall components.
__F__ 19. Vacuoles are bag-like structures that contain the endoplasmic
reticulum.
__T__ 20. Vacuoles are bag-like structures that contain water for the cell to use.
__T__ 21. Only plants have a cell wall.
Fill in the Blank
cells
ribosomes
chloroplasts
cellular respiration
nucleus
proteins
photosynthesis
DNA
amino acid
mitochondria
1. There are several similar structures within the _CELLS_____ of different
organisms.
2. The organelles within a cell must work together to make a cell’s
__PROTEINS_____.
3. The code for the _AMINO ACID______ sequence of a protein is stored in the
_DNA______ molecules.
4. The _NUCLEUS______ is the organelle that holds the DNA molecules.
5. The __RIBOSOMES_________ join together the amino acids to make a
protein.
6. The _MITOCHONDRIA____ provide the energy needed to build proteins by
breaking glucose apart to release its stored energy.
7. _CELLULAR RESPIRATION___ is the name of the process in which glucose is
broken down.
8. __CHLOROPLASTS________ are the organelles that are capable of using light
energy to make glucose.
9. __PHOTOSYNTHESIS_______ is the name of the process in which glucose is
made.
Answer the Following
1. Why are cells called the basic unit of life?
They are the smallest unit considered to be living.
2. What is in the nucleus of a cell? What does it do?
DNA- it tells the rest of the cell what to do.
3. What is the function of ribosomes?
To make proteins
4. What is the function of chloroplasts?
To conduct photosynthesis
5. What is the function of mitochondria?
To conduct respiration.