CELL:Structure and Function

RONALDO T. BIGSANG, M.Sc.Assistant ProfessorScience DepartmentMindanao State University-General Santos City

OUTLINE

Cell Theory: Development and Principles

Prokaryotic vs Eukaryotic Cell: Similarities and Differences

Organelles: Structure and Function

Animal vs Plant Cell: A Comparison

CELL THEORY: Its developmentYear of

Discovery Scientist Contribution

1590 Hans & Zacharias Janssen

Dutch; developed the first compound microscope by combining 2 lenses in a tube

1665 Robert Hooke English; discovered small, hollow compartments in a cork of an oak tree --- cells

1675 Anton van Leeuwenhoek

Dutch; observed tiny living organisms from rainwater, saliva, blood --- animalcules

CELL THEORY: Its developmentYear of

DiscoveryScientist Contribution

1838 Matthias Schleiden German; suggested that plants were made up of cells

1839 Theodor Schwann German; suggested that animals are made up of cells

1840 Jan Evangelista Purkinje

Czech; named the cellular content ‘protoplasm’

1855 Rudolf Virchow German; suggested that all cells come from cells

CELL THEORY: Its principles

1) all living things are made up of cells

2) cells are the basic units of life

3) cells only come from pre-existing cells

CELL is described…

as the basic structural and functional unit of life simplest entity capable of carrying out life’s

processes can exist alone (unicellular) or as a complex

organism (multicellular)

to be composed primarily of C, H, O, N minor elements --- Ca, P, K, S, Na, Cl, Mg, I, Fe trace elements --- Cr, Co, Cu, F, Mn, Mo, Se, Si,

Sn, Va, Zn

CELL is described…

to contain over 60 percent water --- homeostasis (buffering effect)

to have carbohydrates, lipids, proteins and nucleic acids as the major biomolecules

to vary in size --- ranges from 0.2μm to 2mm

to vary in shape --- fixed or variable

Table 1. Various cell types and their sizes.

Table 2. Various cell shapes and their examples.

PROKARYOTIC VS EUKARYOTIC

prokaryotic without true nucleus but a

NUCLEOID region genetic material is in DIRECT

contact with the surrounding environment (cytoplasm)

eukaryotic with true NUCLEUS genetic material is ISOLATED

and PROTECTED from the surrounding environment (cytoplasm)

with ORGANELLES

PROKARYOTIC VS EUKARYOTIC

PROKARYOTIC

Plasma Membrane

with NUCLEOID Cytoplasm

NO nucleus DNA (genetic material)

NO organelles Ribosomes

COMMON EUKARYOTIC(to both)

with NUCLEUS

WITH organelles

PROKARYOTIC VS EUKARYOTIC

despite their differences, prokaryotic and eukaryotic cells have COMMONALITIES Plasma Membrane▪ structural barrier separating the cell from the

outside environment; with protective and regulatory functions

PROKARYOTIC VS EUKARYOTIC

Cytoplasm▪ space in the cell where most

cellular activities take place --- “factory area”

▪ contains an intracellular matrix called cytosol where all other cellular components are suspended

▪ organelles --- membrane-bound structures in in eukaryotic cells

▪ inclusions --- non-permanent and inactive substances/materials in the cell (i.e. fat globules, crystals)

PROKARYOTIC VS EUKARYOTIC

DNA (genetic material)▪ “blueprint” of an organism▪ carries all the information

necessary for the growth, development and survival of an organism

Ribosomes▪ small non-

membrane bound structures that act as sites for protein synthesis in the cell

ORGANELLES --- “little organs” membrane-

bound structures performing a specific function in eukaryotic cells

distribution of work in the cell --- maximizes time and space

ORGANELLES --- “little organs”

NUCLEUS

structure double-membraned

structure with nuclear pores that connect the nuclear components to the cytoplasm

control center of the cell

function directs RNA and protein

synthesis stores the genetic

information (DNA)

ORGANELLES --- “little organs”

NUCLEOLUS

structure spherical organelle

within the nucleus

function assembles ribosomes

ORGANELLES --- “little organs”ENDOPLASMIC RETICULUM structure

network of internal membranes (endomembrane system)

divided into 2 regions:▪ rough ER --- with ribosomes▪ smooth ER --- w/out ribosomes

function compartmentalizes the cell

creating a greater surface area for cellular processes to proceed

serves in the transport of cellular products via the formation of vesicles

rough ER fxn: protein synthesis

smooth ER fxn: lipid synthesis, regulates

calcium levels

ORGANELLES --- “little organs”

GOLGI BODIES

structure stacks of flattened

membranous sacs called cisternae

cis face --- accepts incoming transport vesicles from the ER

trans face --- releases secretory vesicles containing the finished product

function modifies and packages

cellular products

ORGANELLES --- “little organs”

MITOCHONDRION

structure hotdog-shaped structure with

smooth outer membrane, folded inner membrane and many respiratory enzymes

intermembrane space separates the outer and inner membranes

folds of the inner membrane are called cristae

matrix is the space within the inner membrane

function produces ATP (aerobic respiration)

ORGANELLES --- “little organs”

LYSOSOME

structure small spherical bodies

containing digestive or acidic hydrolytic enzymes

function digests macromolecules,

cellular debris, old organelles and foreign substances

ORGANELLES --- “little organs”

PEROXISOME

structure small spherical bodies

containing oxidase enzymes

function neutralizes toxic

substances breaks down fatty acids

ORGANELLES --- “little organs”

VESICLES

structure membrane-bound sacs

function store and transport

substances

ORGANELLES --- “little organs”

VACUOLE

structure membrane-bound sacs in animals, many but

small in size in plants, one big

central vacuole

function store water, enzymes,

pigments, waste products

ORGANELLES --- “little organs”

CHLOROPLAST

structure double-membraned, green

oval structure with stacks of sac-like structures within

thylakoid refers to the sac-like structure containing pigments such as chlorophyll and carotenoids

thylakoids stack together to form a granum

function facilitate food production in

photosynthetic organisms

OTHER CELL STRUCTURES

CYTOSKELETON

structure network of protein filaments

including microfilaments, intermediate filaments, microtubules

cilia and flagella --- motility centriole --- anchor and

assemble spindle fibers in animal mitosis

function provides structural support

and movement (in some) to the cell

OTHER CELL STRUCTURES

CELL WALL

structure rigid structure in plants

and members of the kingdom fungi made up of cellulose or chitin, respectively

function provides structural

support to the cell

PLANT VS ANIMAL CELL

END