CHAPTER 2: CELL BIOLOGY
Cells
- Basic unit of all living things, including humans.
- The body may have quite different structures and functions, yet they share several
common characteristics.
- Highly organized unit (pili lang yung pwedeng pumasok and lumabas)
Plasma membrane/Cell membrane
- Forms the outer boundary of the cell
- Where cell interacts with its external environment
Nucleus
- Located centrally
- Directs cell activities
Cytoplasm
- Where cell activities take place
- Located between the plasma membrane and nucleus where most cell activities take
place
- Contains organelles
Organelles
- Within cells
- Specialized structures that perform specific functions
Characteristic functions of the cell:
1. Cell metabolism and energy use.
a. Involves all chemical reactions that occur within the cell.
b. Metabolic reactions: energy transfers (energy released in one reaction is used by
another reaction)
2. Synthesis of Molecules
a. The different cells of the body synthesize or produce various types of molecules
including protein, nucleic acids and lipids.
b. The structural and functional characteristics of cells are determined by the types
of molecules they produce.
3. Communication
a. Cells communicate with each other by using chemical and electrical signals.
b. Example: nerve cells produce chemical signals by which they communicate with
muscle cells. Then, muscle cells respond to the chemical signals by contracting
or relaxing.
, 4. Reproduction and inheritance
a. Most cells contain complete copies of all the genetic information of the
individual.
b. Genetic information = determines the structural and functional
characteristics of cells.
c. As a person grows, the cell divides to produce new cells, each containing the
same genetic information.
d. Gametes = specialized cells that are responsible for transmitting genetic
information to the next generation.
Summary of Cell parts and functions:
1. Plasma Membrane/ Cell Membrane
a. Lipid bilayer composed of phospholipids and cholesterol
b. Proteins extend across or embedded in either surface of the lipid bilayer
c. Outer boundary of the cell
d. Controls the entry and exit of substances
e. Receptor proteins function in intercellular communication
f. Marker molecules enable cells to recognize one another
g. Passively or actively regulates what enters or leaves the cell.
2. Nucleus
a. Enclosed by nuclear envelope
b. Double membrane with nuclear pores
c. Contains chromatin (dispersed, thin strand of DNA and associated proteins) which
condenses to become visible mitotic chromosomes during cell division
d. One or more nucleoli (consists of RNA and proteins and are site of
e. Dense bodies consisting of ribosomal RNA and proteins
f. Control center of the cells
g. DNA within the nucleus regulates protein synthesis and therefore the
chemical reactions of the cell
h. Contains genetic material of the cell
i. Site of RNA synthesis and ribosomal subunit assembly
3. Cytoplasm
a. The material outside the nucleus and inside the plasma membrane.
b. Cystosol - consists of a fluid part (the site of chemical reactions)
Cytoplasmic organelles:
4. Ribosome
a. Ribosomal RNA and proteins form large and small subunits
b. Some are attached to the endoplasmic reticulum and others are in the
cytoplasm (these are called free ribosomes)
c. Site of protein synthesis
Cells
- Basic unit of all living things, including humans.
- The body may have quite different structures and functions, yet they share several
common characteristics.
- Highly organized unit (pili lang yung pwedeng pumasok and lumabas)
Plasma membrane/Cell membrane
- Forms the outer boundary of the cell
- Where cell interacts with its external environment
Nucleus
- Located centrally
- Directs cell activities
Cytoplasm
- Where cell activities take place
- Located between the plasma membrane and nucleus where most cell activities take
place
- Contains organelles
Organelles
- Within cells
- Specialized structures that perform specific functions
Characteristic functions of the cell:
1. Cell metabolism and energy use.
a. Involves all chemical reactions that occur within the cell.
b. Metabolic reactions: energy transfers (energy released in one reaction is used by
another reaction)
2. Synthesis of Molecules
a. The different cells of the body synthesize or produce various types of molecules
including protein, nucleic acids and lipids.
b. The structural and functional characteristics of cells are determined by the types
of molecules they produce.
3. Communication
a. Cells communicate with each other by using chemical and electrical signals.
b. Example: nerve cells produce chemical signals by which they communicate with
muscle cells. Then, muscle cells respond to the chemical signals by contracting
or relaxing.
, 4. Reproduction and inheritance
a. Most cells contain complete copies of all the genetic information of the
individual.
b. Genetic information = determines the structural and functional
characteristics of cells.
c. As a person grows, the cell divides to produce new cells, each containing the
same genetic information.
d. Gametes = specialized cells that are responsible for transmitting genetic
information to the next generation.
Summary of Cell parts and functions:
1. Plasma Membrane/ Cell Membrane
a. Lipid bilayer composed of phospholipids and cholesterol
b. Proteins extend across or embedded in either surface of the lipid bilayer
c. Outer boundary of the cell
d. Controls the entry and exit of substances
e. Receptor proteins function in intercellular communication
f. Marker molecules enable cells to recognize one another
g. Passively or actively regulates what enters or leaves the cell.
2. Nucleus
a. Enclosed by nuclear envelope
b. Double membrane with nuclear pores
c. Contains chromatin (dispersed, thin strand of DNA and associated proteins) which
condenses to become visible mitotic chromosomes during cell division
d. One or more nucleoli (consists of RNA and proteins and are site of
e. Dense bodies consisting of ribosomal RNA and proteins
f. Control center of the cells
g. DNA within the nucleus regulates protein synthesis and therefore the
chemical reactions of the cell
h. Contains genetic material of the cell
i. Site of RNA synthesis and ribosomal subunit assembly
3. Cytoplasm
a. The material outside the nucleus and inside the plasma membrane.
b. Cystosol - consists of a fluid part (the site of chemical reactions)
Cytoplasmic organelles:
4. Ribosome
a. Ribosomal RNA and proteins form large and small subunits
b. Some are attached to the endoplasmic reticulum and others are in the
cytoplasm (these are called free ribosomes)
c. Site of protein synthesis
