cells and tissues - alderman science...

PowerPoint® Lecture Slide Presentation

by Patty Bostwick-Taylor,

Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART C 3

Cells and

Tissues


Protein Synthesis

Gene—DNA segment that carries a blueprint for

building one protein

Proteins have many functions

Building materials for cells

Act as enzymes (biological catalysts)

RNA is essential for protein synthesis


Role of RNA

Transfer RNA (tRNA)

Transfers appropriate amino acids to the

ribosome for building the protein

Ribosomal RNA (rRNA)

Helps form the ribosomes where proteins are

built

Messenger RNA (mRNA)

Carries the instructions for building a protein

from the nucleus to the ribosome


Transcription and Translation

Transcription

Transfer of information from DNA’s base

sequence to the complimentary base

sequence of mRNA

Three-base sequences on mRNA are called

codons


Transcription and Translation

Translation

Base sequence of nucleic acid is translated to

an amino acid sequence

Amino acids are the building blocks of

proteins


Protein Synthesis

Figure 3.16

Nucleus (site of transcription)

DNA

mRNA specifying one polypeptide is made on DNA template

mRNA leaves nucleus and attaches to ribosome, and translation begins

Synthetase enzyme

Amino acids

Cytoplasm (site of translation )

Correct amino acid attached to each species of tRNA by an enzyme

Growing polypeptide chain

Nuclear pore

Nuclear membrane

mRNA

As the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain

Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid

Direction of ribosome advance; ribosome moves the mRNA strand along sequentially as each codon is read

Small ribosomal subunit

Portion of mRNA already translated

tRNA “head” bearing anticodon

Large ribosomal subunit

Peptide bond

Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon

Codon

Ala

Phe

Ser

Gly

Met

C G G

G U U U C U C C A A G C C A U


Protein Synthesis

Figure 3.16, step 1


DNA



Nuclear pore

Nuclear membrane

mRNA


Protein Synthesis

Figure 3.16, step 2


DNA




Nuclear pore

Nuclear membrane

mRNA



Codon

U G C C A U


Protein Synthesis

Figure 3.16, step 3


DNA



Synthetase enzyme

Amino acids



Nuclear pore

Nuclear membrane

mRNA



Codon

U G C C A U


Protein Synthesis

Figure 3.16, step 4


DNA



Synthetase enzyme

Amino acids



Nuclear pore

Nuclear membrane

mRNA





Codon

U G C C A U


Protein Synthesis

Figure 3.16, step 5


DNA



Synthetase enzyme

Amino acids




Nuclear pore

Nuclear membrane

mRNA






Peptide bond


Codon

Ala

Phe

Ser

Gly

Met

C G G

G C U C A G C C A U


Protein Synthesis

Figure 3.16, step 6


DNA



Synthetase enzyme

Amino acids




Nuclear pore

Nuclear membrane

mRNA


Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid



Portion of mRNA already translated



Peptide bond


Codon

Ala

Phe

Ser

Gly

Met

C G G

G U U U C U C C A A G C C A U


Body Tissues

Tissues

Groups of cells with similar structure and

function

Four primary types

Epithelial tissue (epithelium)

Connective tissue

Muscle tissue

Nervous tissue


Epithelial Tissues

Locations

Body coverings

Body linings

Glandular tissue

Functions

Protection

Absorption

Filtration

Secretion


Epithelium Characteristics

Cells fit closely together and often form sheets

The apical surface is the free surface of the tissue

The lower surface of the epithelium rests on a

basement membrane

Avascular (no blood supply)

Regenerate easily if well nourished


Epithelium Characteristics

Figure 3.17a


Classification of Epithelia

Number of cell layers

Simple—one layer

Stratified—more

than one layer

Figure 3.17a


Classification of Epithelia

Shape of cells

Squamous

flattened

Cuboidal

cube-shaped

Columnar

column-like

Figure 3.17b


Simple Epithelia

Simple squamous

Single layer of flat cells

Usually forms membranes

Lines body cavities

Lines lungs and capillaries


Simple Epithelia

Figure 3.18a


Simple Epithelia

Simple cuboidal

Single layer of cube-like cells

Common in glands and their ducts

Forms walls of kidney tubules

Covers the ovaries


Simple Epithelia

Figure 3.18b


Simple Epithelia

Simple columnar

Single layer of tall cells

Often includes mucus-producing goblet cells

Lines digestive tract


Simple Epithelia

Figure 3.18c


Simple Epithelia

Pseudostratified columnar

Single layer, but some cells are shorter than

others

Often looks like a double layer of cells

Sometimes ciliated, such as in the respiratory

tract

May function in absorption or secretion


Simple Epithelia

Figure 3.18d


Stratified Epithelia

Stratified squamous

Cells at the apical surface are flattened

Found as a protective covering where friction

is common

Locations

Skin

Mouth

Esophagus



Figure 3.18e



Stratified cuboidal—two layers of cuboidal cells

Stratified columnar—surface cells are columnar,

cells underneath vary in size and shape

Stratified cuboidal and columnar

Rare in human body

Found mainly in ducts of large glands



Transitional epithelium

Shape of cells depends upon the amount of

stretching

Lines organs of the urinary system



Figure 3.18f


Glandular Epithelium

Gland

One or more cells responsible for secreting a

particular product


Glandular Epithelium

Two major gland types

Endocrine gland

Ductless since secretions diffuse into

blood vessels

All secretions are hormones

Exocrine gland

Secretions empty through ducts to the

epithelial surface

Include sweat and oil glands

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