The Human Body A multicellular organism. The cell.

From cells to organisms

Human beings are

composed of

biomolecules.

They are made up of

cells.

They perform 3 vital

functions:

◦ Nutrition

◦ Reaction to stimuli

◦ Reproduction

Cell size

Microscopic objects are

meassured in:

◦ μm = 10-3 mm

◦ nm = 10-6 mm

These are not visible

with a naked eye.

Eye resolution is 0.2 mm

◦ If two objects are

separated by a smaller

distance, we will see them

as one.

Exercise:

If an object meassures 1 mm, how many micrometers does it meassure? And how many nanometers?

Activity

5 cm

Image increased: 1500 times

How large is the

Paramecium in

reality?

5cm

1500

= 0,0033 cm How many µm is that?

33 µm

Biomolecules

Rich in carbon

◦ Proteins: give

structure..transport…

muscle.

◦ Lipids: fat

◦ Carbohidrates: sugar

◦ Nucleic acids: form the

nucleus. Genetic

material.

What do all cells have in common?

Cellular membrane

Cytoplasm

Nucleus

Cell membrane

It is a thin layer that covers the cell and serves

as a boundary between the cell and the

surrounding.

Cytoplasm

Inner content of the cell mainly made of

water and where different structures,

called organelles, are found.

Organelles: Nucleus It is the largest and most visible structure in the

cell. It’s shaped like a sphere and normally in the

center of the cell. It contains the material necessary

to control all cell functions.

Nuclear envelope: made of a double membrane which

has pores that allow the exchange of substances

Chromatin: filaments of genetic material which has

the information that controls how the cell functions

Nucleolus: The ribosomes are synthesized in here

It’s structure changes depending on the phase of the

cell cycle. The chromatin condenses into structures

called chromosomes during cell division.

CONTROL

Activity How many cells

do you see in

the image?

The cell: organelles

Organelles: Mitochondria

• All cells need mitochondria to obtain energy from nutrients

• Mitochondria have an oval shape with a double membrane.

• The cell obtains energy from small organic molecules using

oxygen through a process called cellular respiration

• http://www.shmoop.com/biology-cells/botw/resources?d=http://multimedia.mcb.harvard.edu/

With

OXYGEN

Respiration

http://www.youtube.com/watch?v=xbJ0nbzt5Kw&feature=relmfu

http://www.youtube.com/watch?v=3y1dO4nNaKY&feature=relmfu

Organelles: Endoplasmic

Reticulum

• It’s made of membrane

canals and sacks that extend

throughout the cytoplasm

with grain like structures

called ribosomes.

• Rough ER

• In the reticulum many

different substances are

produced.

• The ER without ribosomes is

the Smooth ER.

Organelles: Lysosomes

• Membrane bound vesicles that transform complex structures into simpler ones.

• Some nutrients reach the cell already transformed in small molecules. If not they are digested into smaller molecules by the lysosomes.

Organelles: Vacuoles

Membranous

vesicles which

store dissolved

substances as

reserves or waste.

Membrane of

vacuoles in plant cells

Organelles: Ribosomes

Small particles

found loose in the

cytoplasm or

attatched to the

ER membrane.

They synthesize

proteins.

They are produced

in the nucleolus.

Organelles: Centrioles

2 hollow ciliders

which walls are

made of

filaments.

They are in

charge of moving

the cytoskeleton

and play a main

role in cell

division.

Organelles: cytoskeleton

Group of filaments that are

distributed making a network

around the cytoplasm.

Most of the time cells respond

with movements to stimuli.

The structures responsible for

this movement are the filaments

of the cytoskeleton