The Cell Structure & Function

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Draw or label the principle parts

of a typical cell and list or

recognize their functions.



Plasma Membrane



Plasma (Cell) Membrane

Encloses cell contents

Regulates the movement of materials into and out of cell

Plays role in cellular communication



Nucleus Nuclear Membrane



Nucleus

Control Center of Cell

Nuclear Membrane

Mediates movement of materials into and

out of the nucleus



Cytoplasm



Cytoplasm

• Area between plasma and nuclear

membranes which acts as the factory of the

cell

• Contains cytosol (water), inclusions (stored

materials) and cytoplasmic organelles



Nucleolus

Chromosomes

(Chromatin)



Nucleolus

• Site of ribosome subunit synthesis

Chromosomes (Chromatin)

• Storage of genetic information



Endoplasmic Reticulum



Vacuole

Lysosome

Ribosome



Vacuole

• Storage

Lysosom

e• Site of intracellular digestion

• Protection against infection

Ribosome

• Site of protein synthesis



Golgi ComplexMitochondrion



Golgi Complex

• Packages protein secretions for export

• Makes Lysosomes

Mitochondrion

• Power plant of cell (Makes

ATP)



Centrioles

Cilia

Flagellum



Centrioles

• Produce spindle fibers for mitosis & microtubulesfor intracellular support

Cilia

• Move materials along surface of cell

Flagellum

• Moves the entire cell



Microfilaments and

Microtubules

• Form the internal cytoskeleton of the cell

• Allow for cell mobility & movement of cellparts

• Assist with intracellular transport

• Provide structure for cilia and flagellae



Recognize from diagrams or

draw the molecular structure of

DNA and RNA

• DNA and RNA are both nucleic acids

• Nucleic acids are made up of long chains of nucleotide

subunits.



NS

P

The Phosphate group, Sugar molecule and Nitrogenous base

are bonded together in a particular arrangement with covalent bonds to form a nucleotide



Nucleotides are bonded together

to form nucleic acid molecules

NS

P

NS

P

NS

P



Structural Characteristics of

RNA• RNA is made up of a single strand of RNA

nucleotides

• RNA nucleotides contain the sugar Ribose• Each RNA nucleotide contains one of the

following nitrogenous bases:

Adenine - (A)Uracil - (U)

Cytosine -

(C) -



RNA

AR P

UR

P

CR

P

GR

P



RNA Functions

• RNA carries genetic information from the

nucleus to the ribosomes for the synthesis

of protein• At the ribosomes, RNA carries out genetic

instructions to synthesize protein

• The process through which RNAsynthesizes protein is called translation



DNA Structural Characteristics

• DNA is made up of a double strand of DNAnucleotides

• DNA nucleotides all contain the sugar

deoxyribose• Each DNA nucleotide contains one of the

following nitrogenous bases:

Adenine - (A)Thymine - (T)

Cytosine - (C)

Guanine - (G)



DNA

T DP

ADP

TDP

CD

P

A D

P

G D

P



T DP

ADP

TDP

CDP

AD

P

GD

P

Notice That:

The base Adenine

(A) always pairs

with the base

Thymine (T) inDNA

The base Cytosine

(C) always pairs

with the base

Guanine (G)



The chemical bonds between the

bases in each strand hold the

DNA molecule together

T DP

ADP

TD

P

CDP

A

D

P

G D

P

Si l i h h d



Since alternating Phosphates and

Sugars always form the backbone of

each strand,

T DP

ADP

TDP

CD

P

A DP

G D

P

A T

T A

C G

U

A

G

DNA & RNA molecules are often

illustrated as lines with bases attached.



The two strands of DNA nucleotides coil

to form a double helix



If this represents the base

sequence on one half of a DNA

moleculeWhat would the base sequence of the other half be?

A

T

G

C

A

T

T

A

G

T

C

A



DNA Functions

• Stores genetic information

• Replicates (copies) itself to passgenetic information to next

generation



The halves of the DNA strand separate &

each serves as a pattern to form the other half

Th DNA l



A

DNA

polymerase

T

G

C

A

T

T

A

C

T

G

C

A

T

T

A

C

A T

A

C

G

T

A

A

T

G

T

A

C

G

T

A

A

T

G

The enzyme DNApolymerase

catalyzes DNA replication



Through replication one DNA strand

separates to form two identical strands



DNA Functions


• Replicates (copies) itself to passgenetic information to next generation

• Makes RNA



The halves of the DNA strand separate & one

serves as a pattern for making RNA



A

T

C

T

A

G

U

A

G

A

U

C

RNA



DNA Functions


• Replicates (copies) itself to pass genetic

information to next generation

• Makes RNA

• Supplies genetic instructions to RNA for the

synthesis of specific proteins



The process through which

DNA makes RNA is calledtranscription

• The enzyme RNApolymerase catalyzes the

reactions involved in transcription.

• After transcription is complete, the two

halves of the DNA molecule rejoin to

reform a double strand.

• The section of DNA used to synthesize

Messenger RNA is called a gene.



Transcription

RNA

polymerase

• Each 3 base sequence on mRNA is called a codon.

(Gene)

• Each codon has the code for a certain amino acid.

• RNApolymerase is the enzyme which catalyzes the

transcription of RNA.



Three types of RNA may be

transcribed in this way.

• Messenger RNA (mRNA)

• Ribosomal RNA (rRNA)

• Transfer RNA (tRNA)

Each type has a unique function

in protein synthesis



Messenger RNA (mRNA)

• Receives genetic instructions from a gene on achromosome in the nucleus.

• Carries genetic instructions for making aspecific protein to the ribosomes.



Transcription

To Cytoplasm



Ribosomal RNA (rRNA)

• Long-lived RNA that is the major component of ribosomes.

Ribosome(rRNA)

•Ribosomes are the sites of protein synthesis in

the cytoplasm.



Ribosome(rRNA)

mRNA

• Ribosomal RNA acts together with

Messenger RNA to make protein using thecode it carries from the nucleus.



E h tRNA l l h th



Each tRNA molecule has a three

base sequence called an

anticodon

• The anticodon on tRNA can pair with the

codon on mRNA if the bases are

complementary.



Depending on the code on each

tRNA anticodon,

• Each tRNA molecule carries a

certain Amino Acid.



Ribosomal RNA (rRNA)

• Ribosomal RNA acts together with Transfer

RNA and Messenger RNA to make protein

using the instructions provided byMessenger RNA and the amino acids

supplied by Transfer RNA.

• The process through which mRNA, rRNAand tRNA work together to make protein is

called translation.



Ribosome

(rRNA)

mRNA

As anticodons on tRNA pair with codons on mRNA,

amino acids are arranged in the specific sequence to

form the protein being synthesized.



Ribosome

(rRNA)

mRNA

As amino acids are arranged in order, peptide bonds

form between them to form a polypeptide chain.



As translation is completed, the

polypeptide chain (protein) isreleased by tRNA.



The newly synthesized protein is

free to carry out its functionwithin the cell.



DNA Functions


• Replicates (copies) itself to pass genetic

information to next generation

• Makes RNA

• Supplies genetic instructions to RNA for the

synthesis of specific proteins



Gene: A segment of DNA with

the code for synthesizing aspecific polypeptide ( protein)

Genetic Code: The sequence of



Genetic Code: The sequence of

base triplets within a gene that

dictate the sequence of amino

acids needed to form a specific

polypeptide (protein)

Code



Genetic Diseases may be caused

by:• The lack of genes needed to make

essential proteins which serve as enzymes

or structural parts of cells.

• Phenylketonuria (PKU) is an example of this type of disease.



Genetic Diseases are caused by:

•Mistakes in the code within a gene which cause proteins

to be made that don’t function normally or are not able to

carry out their intended functions.

Hemoglobin transports Oxygen



Hemoglobin transports Oxygen

and Carbon Dioxide inside Red

Blood Cells



A change of a single amino acid out of 287 in

one globin molecule causes the globin to form

stiff, sharp spikes when oxygen content is low.

Normal red blood cells have



Normal red blood cells have

smooth surfaces so they can easily

pass through blood vessels.

Cells with abnormal hemoglobin get stuck &

block circulation causing extreme pain andoxygen deficit in victims.

This condition is called Sickle Cell Anemia.



Diagram or recognize from

diagrams the sequential stages of the cell cycle.

• The cell cycle includes two main periods.• Interphase in which the cell grows and

carries out its normal metabolic activities.

• Mitosis, during which time the nucleus andthe cytoplasm of the cell divide.

Cell Cycle



Cell Cycle



Interphase



Interphase is divided into three

parts:• Gap 1 (G1) during which the cell synthesizes proteins

rapidly and increases in size.





parts:

• Snythetic phase (S) during which DNA replicates itself

and growth and normal metabolic activities continue.





parts:

• Gap 2 (G2) during which growth and

metabolism continues and centrioles

complete their replication.



Mitosis or nuclear division is

divided into four phases

• Prophase

• Metaphase

• Anaphase

• Telophase



During Prophase:

• The nuclear membrane disappears.



During Prophase:

• The nucleolus disappears.



During Prophase:

• Centrioles move to opposite sides of the cell.



During Prophase:

• Chromatin condenses to form chromosomes.

V V

V V

V V

V V



Metaphase is characterized by:• Chromosomes lining up on the equator of the

cell as spindle fibers pull from each centriole.

V V

V V

V V

V V

Each chromosome is made up of



Each chromosome is made up of

two identical DNA strands called

chromatids

ChromatidChromatid



Anaphase

• Chromatids are pulled to opposite centrioles

V V

V V

V

V

V

V



T l h



Telophase

• Spindle fibers connecting chromatids tocentrioles disappear.

V V

V

V

V

V

V

V

T l h



Telophase

• A nuclear membrane appears around eachcluster of chromatids.

V

V

V

V

V

V V

V

T l h



Telophase

• Nucleoli reappear in each nucleus.

V

V V

VV

V V

V

T l h



Telophase

• Chromatids disperse to form chromatin.



Telophase



Telophase

• The division of the cytoplasm into two cellsis called cytokinesis.



When cytokinesis is complete,Mit i d & h ll b i



Mitosis ends & each cell begins

G1 of Interphase

G 1G 1



Mitosis is significant because:

• It is the means by which cells divide.

• It is how we grow from a single fertilized

ovum into individuals composed of billionsof cells.

• It is the means by which we replace cells

that die or are lost during our life.• It is how healing occurs.



In Mitosis:

• The number of chromosomes in each cell

does not change.

• Human cells start out with 46chromosomes.

• The daughter cells produced through

mitosis are genetically identical with eachhaving 46 chromosomes.

Known things which stimulate



Known things which stimulate

cells to divide include:

• Loss of contact inhibition between cells or space

for cell growth.

• Changes in cell surface area to volume

relationships.

• Chemical messengers.

The Cell Structure & Function

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