Life is Cellular Cell Structures & Functions Biology I

Introduction to Cells Before the 17th century, no one knew cells existed Most cells are too small to be seen with the unaided eye In the early 17th century microscopes were invented & cells were seen for the 1st time Anton Von Leeuwenhoek, a Dutchman, made the 1st hand-held microscope & viewed microscopic organisms in water & bacteria from his teeth In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls Hooke named what he saw "cells“

 The combined work of scientists Schleiden, Schwann, & Virchow is known as the Cell Theory : Principles of the Cell Theory All living things are made of one or more cells Cells are the basic unit of structure & function in organisms Cells come only from the reproduction of existing cells The Cell Theory

Cell Diversity Not all cells are alike Cells differ in size, shape, and function The female egg cell is the largest cell in the body & can be seen without a microscope Bacterial cells are some of the smallest cells & are only visible with a microscope

Cells come in a variety of shapes, & the shape helps determine the function of the cell (e.g. Nerve cells are long to transmit messages in the body, while red blood cells are disk shaped to move through blood vessels)

Basic Structure of a Cell

Introduction to Cells  Cells are the basic units of organisms  Cells can only be observed under microscope  Basic types of cells: Animal CellPlant Cell Bacterial Cell

Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells

 Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles  Eukaryotes include most other cells, have a nucleus and membrane-bound organelles Cells May be Prokaryotic or Eukaryotic

Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes to make proteins in their cytoplasm

Prokaryotic Cell - Bacteria

Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles

Eukaryotic - Animal Cell

Eukaryotic - Plant Cell

Two Main Types of Eukaryotic Cells Plant Cell Animal Cell

Cytoplasm Entire region between the nuclear membrane and the cell (plasma) membrane. This includes all organelles! Jelly-like substance enclosed by cell membrane cytoplasm Cytoplasm

Nucleus Membrane-bound cellular organelle in eukaryotes. Contains the genes (DNA) Brain of the cell (controls all activities) nucleus

Large membrane- closed sac for cellular storage. Contains sugars, proteins, minerals, wastes, & pigmentsVacuoles Vacuole

Organelles Found in Cells  Nucleolus – makes ribosomes  Lysosomes – digests & gets rid of wastes  Golgi Bodies– wrap & export proteins ( Modifies, stores and routes products from the ER to the plasma membrane)  Ribosomes- site of protein synthesis incoming small subunit polypeptide mRNA

Smooth & Rough Endoplasmic Reticulum Smooth ER lacks ribosomes & makes proteins used in the cell Rough ER has ribosomes on its surface & makes proteins to export

Mitochondria Found in both plants and animal cells. It is the site of cellular respiration, a process that uses energy extracted from organic macromolecules (like glucose) to produce ATP. Also known as the “powerhouse” Outer membrane Inner membrane

Chloroplast Outer Membrane Inner Membrane Stroma Granum Thylakoid Found in photosynthetic plants cells. The site of photosynthesis, a process that uses light energy (sun) and water to produce organic macromolecules (glucose).

Plasma (Cell) Membrane The boundary of every cell Separates the living cell from its nonliving surroundings. Acts as a selective barrier Made of protein and phospholipids Hydrophobic region Hydrophilic region

Network of fibers through out the cytoplasm. Aids in cellular support and movement. Composed of three components: 1.Microfilaments - support and cellular contraction 2.Intermediate filaments - support 3.Microtubles - support and cell motility

Cilia and Flagella Extensions of the plasma membrane. Aids in movement….

Cell Wall Strong cellulose fibers surrounding plant cells and some bacteria only! Composed of polysaccharides and proteins. Freely permeable Cell wall Protect and support the enclosed substances Resist entry of excess water into the cell Give shape to the cell

Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

Differences between plant cells and animal cells Animal cellsPlant cells Relatively smaller in size Irregular shape No cell wall Relatively larger in size Regular shape Cell wall present

Animal cellsPlant cells Vacuole small or absent Glycogen as food storage Nucleus at the center Large central vacuole Starch as food storage Nucleus near cell wall Differences between Plant Cells and Animal Cells

Levels of organization Cells are grouped together and work as a whole to perform special functions

Levels of Organization  CELLS (muscle cells,nerve cells)  TISSUES (muscle, epithelium)  ORGANS (heart, lungs, stomach)  SYSTEMS (circulatory system)  ORGANISM (human) It’s You!