Cell Structure Biology Sheet printable pdf download

Cell Structure – Human

Structure

Basic Components of Cell:

cell is basic unit of all life; structural and functional

a. cell membrane

- boundary

if its alive, must contain at least a single cell

b. cytoplasm (=cytosol)

the function of an organism is the summation of

– includes everything except

functions of its individual cells

cell membrane

cell first described 300 years ago by Robert Hook

c. nucleus

-genetic material

in human body

d. organelles & inclusions

internal structures

- highly organized, specialized

single fertilized egg ! 75–100 trillion cells (adult)

structures

[>10x’s more bacterial cells in body]

1. Cell Membrane

There are about 200 different kinds of cells in the

human body with a variety of sizes and shapes

defines boundary

human cells range in size from:

!phospholipids, proteins, cholesterol

eg. sperm cells are some of the smallest human cells

phospholipids have polar and nonpolar ends

eg. human eggs & fat cells are some of the largest, barely

tend to arrange themselves into double

visible to naked eye

layered films

eg. some nerve cells are 3 ft long (humans)

framework for all membranes of cells

while there is a great diversity in size and shape

!less diversity in function

help to provide a high capacity for self repair

in most:

proteins “float” randomly in this bilayer

= “fluid mosaic”

Microscopy , Cells, Tissues: Cell Structure – Animals/Humans; Ziser Lecture Notes, 2012.3

some membrane protein functions:

contains genetic material:

eg. receptors (ie. docking sites) for specific

genetic material

substances

eg. carriers: move specific solutes across

=chromosomes

membrane

100’s times length of cell

eg. enzymes: energy transforming enzymes

humans ~3’ of DNA/cell

the cell membrane is selectively permeable

4. Nucleolus

some things enter freely, some things cannot

cross or cross only with “help”

densely packed chromosome region within

nucleus

2. Cytoplasm (=Cytosol)

with proteins and ribosome precursors

contains mostly water, ions, organic molecules etc

site of RNA synthesis

variety of enzymes eg. glycolysis

important in formation of ribosomes

3. Nucleus

5. Mitochondria:

largest of internal cell structures

about size of small bacterial cell

number varies: one to many

contain their own set of DNA (genes):

in humans

passed only from mother to child

most cells have one nucleus

mtDNA remains unchanged generation after generation

RBC’s have none

except by slow random mutation

a few cells are multinucleate (2-50 nuclei)

! used as molecular clock to trace evolution of groups

surrounded by nuclear envelope

eg. all humans today descended from a single

same structure and cell membrane

woman of about 200,000 years ago =

mitochondrial EVE

Microscopy , Cells, Tissues: Cell Structure – Animals/Humans; Ziser Lecture Notes, 2012.3

Cell Structure Biology Sheet

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