7- Differentiation 2D1 - PPT slides

Cellular Differentiation

Potency

Stem Cells

Cellular Differentiation

 _{Process of producing specialized cells}

 _{Specialized cells have physical and chemical}

differences that allow them to perform a function that is different than other cells

 _{All specialized cells come from pre-existing}

Proliferative Potential: Potency

 _{A cell’s potential}

to differentiate

 _{Levels of}

Totipotent

 _{Capable of giving rise to any and all cell types}

 _{Somatic cells}

 _{Germ cells}

 _Placenta

 _{Can form a whole organism / embryo}  _{Totipotent cells:}

 _{zygote – fertilized egg}

Pluripotent

 _{Capable of giving rise to many cell types}

 _{Somatic cells}

 _{Germ cells}

 _{Can not develop into an organism because}

incapable of producing placenta

Blastocyst

 _{Differentiation begins}

 _{Inner cell mass: becomes the embryo and}

some extraembryonic tissue

 _{(Outer) Trophoplast: becomes the placenta}

Multipotent

 _{Can give rise to multiple, but limited number}

of lineages

 _{Committed to produce specific cell types and}

thus specialization potential is limited to one or more cell lines

 _{Adult / Tissue / Somatic stem cells: found in}

Types of Adult Stem Cells

Lineage Differentiated cells

Hematopoietic RBC, WBC, platelets etc.

Intestinal Cells on lining of large and small intestine

Neural Astrocyte, oligodendrocytes, neurons

Mesenchymal

bone, cartilage, fat, cells that support the formation of blood, and fibrous connective tissue

Unipotent

Terminally Differentiated

 _{Cells that are unable to divide}  _{Example: neurons, adipocyte,}

cardiomyocyte, skeletal muscle cells, skin cells

Stem cell division. A – stem cells;

B – progenitor cell; C – differentiated cell;

1 – symmetric stem cell division; 2 – asymmetric stem cell division; 3 – progenitor division;

4 – terminal differentiation

http://en.wikipedia.org/wiki/File:Stem_cell_division_and_differentiation.svg

Stem Cells

 _{Unspecialized /}

undifferentiated cell

 _{Has the potential of becoming}

a specialized cell with a specific function

 _{Property of self-renew for long}

periods of time (immortal)

 _{Formed during the}

development of the embryo

Stem cell division.

A – stem cells

Types of Stem Cells

 _{Embryonic stem cells}

 _{Totipotent or pluripotent}

 _{Adult / Tissue / Somatic stem cells}

 _{Exist within specialized tissue}

 _{Able to differentiate into certain types of cells}

Comparing Potency

Potency Type of stem cell Location of cells

Totipotent Embryonic stem cell Zygote, morula

Pluripotent Embryonic stem cell Blastocyst

Multipotent Adult / Tissue /

Somatic stem cell

The “typical” animal cell

The “typical” plant cell

Specialized Cells

 _{Differentiation not only affects function but}

also structure

 _{Cells physically look different from each}

other

 _{Complex organisms contain many different}

types of cells that perform different functions

 _{Specialized cells have physical and chemical}

Specialized Plant Cells:

Specialized Plant Cells:

Specialized Plant Cells:

Specialized Animal Cells:

Specialized Animal Cells:

skin cells

Specialized Animal Cells:

 _{Cross-section:}

bundles of muscle fibres

 _Longitudinal

section: striations

Specialized Animal Cells:

Specialized Animal Cells:

Specialized Animal Cells:

Specialized Animal Cells:

 _{Large, central}

droplet of fat pushes the

nucleus to one side.

Specialized Animal Cells:

Specialized Animal Cells:

nerve cell (neurons)

Specialized Animal Cells:

Specialized Animal Cells:

Specialized Animal Cells:

Tissue Types

 _{A collection of similar cells that perform a}

specialized function

 _{4 major types:}

Muscle Tissue

 _{Bundles of long cells}

 _{Capable of shortening or contracting}  _{Function: movement}

Muscle Tissue

 _{Classified based}

on 3 cell types

Type Example Control Fatigue

Resistance

Cardiac Heart Involuntary Very

Skeletal Limbs Voluntary Not

Smooth Organs that contract (e.g. stomach,

Tissue Types

 _{A collection of similar cells that perform a}

specialized function

 _{4 major types:}

 _{Neurons that interact with each other}  _{Conduct electrical impulses}

 _{Communicates within the body}  _{Example: brain}

Tissue Types

 _{A collection of similar cells that perform a}

specialized function

 _{4 major types:}

Tissue Types

Connective Tissue

 _{Function: structural support, insulation}  _{Example: bone, cartilage, fat, blood}

 _{Cells are held together by a liquid / solid / gel}

Types of Connective Tissue

Tissue Types

 _{A collection of similar cells that perform a}

specialized function

 _{4 major types:}

Epithelial Tissue

 _{Thin sheets of tightly packed cells lining}

organs

 _{Classification:}

 _{Number of cell layers: simple, stratified}

Classification of Epithelial Tissue

Classification

of Epithelial

Tissue

Types of Epithelial Tissue

Epithelial Tissue Location & Function

Location Function

Simple Squamous

• Blood vessels

• Air sacs in lung

• reduce friction

• absorption of nutrients/oxygen

• secretion of waste and CO2 Simple

Cuboidal

• Kidney

• Glands

• Secretion and reabsorption of water, ions, other small molecules Simple

Columnar

• Digestive tract • Absorption of nutrients

• Secretion of mucous Stratified

• Squamous

• Cuboidal

• Columnar

• Skin

• Mouth, esophagus, larynx

• Sweat, salivary, mammary glands

• Bladder, urethra, ureter

• Vagina

• Protection against abrasion

Simple Columnar Epithelial Cells:

Digestive tract (ileum)