SNC2D 01 06 Cell Specialization -...

Cell  Specialization

SNC2D1  Cells,  Tissues  and  Organs

Why  Specialize?

• A  single  cellular  organism  performs  all  required  functions  in  one  cell.

• e.g.,  Amoeba.

Why  Specialize?

• Multicellular  organisms  are  much  more  complex.  

• The  body  needs  to  supply  food  and  nutrients,  transport  materials,    remove  wastes  and  fight  infection.  

Cellular  Differentiation

• The  process  of  creating  specialized  cells.• All  cells  in  the  body  originated  from  the  zygote  undergoing  mitosis.

• As  an  embryo  develops,  cells  change  their  shape,  contents  and  function.

What  Causes  Specialization?

1.    Cytoplasm  Differences:• Asymmetric  distribution  of  

organelles  &  other  factors  in  zygote.

• Results  in  different  daughter  cells.

What  Causes  Specialization?

2.    Environmental  Conditions:• Variations  in  temperature  and  nutrients.  

3.    Neighbouring  Cells:  • Substances  produced  by  nearby  cells  can  

diffuse  to  nearby  cells.

What  Causes  Specialization?

• The  three  factors  listed  may  result  in  the  expression  of  different  genes  within  a  cell.

Abnormal  Development

• Chemical  contamination  of  the  environment  can  affect  cellular  development.

Tissue  Types• Tissues are  a  collection  of  similar  cells  that  perform  specific  functions.

• Animals  have  4  types                                                                                                                                                      of  tissue:1.    Epithelial.2.    Muscular.3.    Connective.4.    Nervous.      

Epithelial  Tissue• Line  the  internal  and  external  surfaces  of  the  body.  

• Form  a  barrier  by  connecting  adjoining  cell  membranes.

Muscular  Tissue• Move  the  body  or  organ  by  contracting  and  relaxing.

Connective  Tissue• Strengthens,  supports  and  protects  other  tissues.• Cells  are  in  an  extracellular  matrix.

Nervous  Tissue

• Made  of  neurons  with  long  projections  that  send  and  receive  signals.

• Coordinates  body  actions.

Tissues  in  the  Arm

From  Conception  to  Birth

Tissues  Assignment

1. Read  the  handout  “Tissues  of  the  Human  Body”  and  learn  the  tissue  subtypes.

2. Answer  the  questions  on  the  handout.

Stem  Cells

• Cells  that  can  differentiate  into  many  different  cell  types.      

• The  daughter  cells                                                                                                                                                            have  the  same  DNA,                                                                                                                                                                                            but  different  genes                                                                                                                                                                  may  be  turned  on                                                                                                                                                        or  off.

Watch  This!!!

https://www.youtube.com/watch?v=cEB8656TCIE

WHAT  IS  A  STEM  CELL?!?!?

Types  of  Stem  Cells

1. Embryonic  Stem  Cells– Differentiates  into  any  cell  type.

2.    Adult  Stem  Cells– Exists  in  some  tissues  but  can  only  form  specific  

types  of  cells.    – E.g.,  bone  marrow  stem  cells  form  white  blood  

cells,  red  blood  cells  and  platelets.

Stem Cells

Stem  Cell  Research

Uses of Stem Cells• embryonic stem cells are found in embryos that are less than a week old

• scientists obtain these cells from eggs fertilized in vitro (outside the womb)

• sources are usually unused embryos from fertility clinics

• obtaining stem cells destroys the embryo

• some people consider this use to be taking a human life