Download • The basic units of a living system or organism

Cells
• The basic units of a
living system or
organism
Cell Theory –
•  developed by 3 German
scientists:
•  Matthias Schleiden,
•  Theodor Schwann,
•  and Rudolf Virchow
These scientists discoveries led to
the cell theory…
What is the CELL THEORY???
Theory that states…
1.  All organisms are made of one or
more cells.
2.  The cell is the basic unit of life
which can perform life processes.
3.  All cells come from other living
cells.
How do we know cells exist?
•  Invention of the microscope made it
possible for people to discover and learn
about cells
•  Robert Hooke looked at cork cells
• 
Anton van Leuenhock used a simple
microscope and was the first person to
see microorganisms.
2 Types of Cells:
•  Prokaryotic - Cells that don’t
have a membrane-covered nucleus
for example: bacteria
•  Eukaryotic – Cells with a nucleus
covered by a membrane for
example: plant and animal cells
Prokaryote
Eukaryote
How are cells
organized?
Ø  Complex living things are
organized into 5 levels.
Ø  Cells carry on the
processes that keep us
alive.
Examples:
Red Blood Cells
Muscle Cells
Skin Cells
ORGANISM (BODY)
ORGAN SYSTEM
ORGANS
TISSUES
CELLS
Representative Animal Cell
Animal Cell
Representative Plant Cell
Plant Cell
Organelles
• -Tiny cell structures that are
specialized parts of a cell
that have specific
functions – a cell “organ.”
CELL MEMBRANE
•  – “gate keeper”
•  outer boundary (or layer) of
the cell
•  controls the movement of
materials into and out of the
cell
CELL WALL
•  found in plant cells
•  tough rigid boundary – made
of cellulose
•  gives cells their shape (it also
provides protection, as well
as support)
CYTOPLASM
•  – “cell fluid”
•  a gel-like material inside the
cell
•  Many cellular activities occur
here and where the organelles
are contained
NUCLEUS
– “brain
of the cell”
•  controls cell processes
•  Contains DNA or chromosomes
- the heredity material or
genetic blueprint of the cell
DNA
•  Hereditary material
•  Chromosomes
–  DNA
–  Protiens
–  Form for cell division
•  Chromatin
NUCLEAR MEMBRANE
•  – materials pass in and out
through tiny holes called
porins
Nucleolus
•  Most cells have 2 or more
•  Directs synthesis of RNA
•  Forms ribosomes
CHLOROPLASTS
•  – “energy
processing organelles”
•  found only in plant cells
•  place where food is made for
plant cells
MITOCHONDRIA
•  – “powerhouse”
•  converts food (glucose) to
energy (ATP)
RIBOSOMES
•  – “protein factories”
•  place where protein is made in
the cells
•  some are attached –
some float in the
cytoplasm
ENDOPLASMIC RETICULUM
•  – “conveyer belt”
•  transports synthesized proteins
throughout the cell
GOLGI BODIES (Apparatus)
•  sort, modify, process, and ship
the proteins through the cell
•  (Also known
As GOLGI
Apparatus)
VACUOLES
“storage”
•  store water, sugar, salts,
nutrients, & wastes in cells
•  maintains the proper pressure
to provide structure
and support in
plant cells
•  –
LYSOSOMES
•  contain chemicals that break
down waste materials.
Unicellular organisms
•  Some organisms only consist of a single
cell
•  But these do usually have the components
of cells (nucleus, membrane etc)
Image Credit Paramecium
What is a unicellular organism?
•  Any life form that consists of a
single cell.
•  They can move, digest food, and
reproduce.
Euglena
•  Environment: Ponds or puddles with rich organic
matter.
•  Movement: By flagella
•  Important Structures:
–  Cell Membrane
–  Nucleus: controls cell activities and contains DNA
–  Flagellum: helps to move
–  Chloroplast: helps with photosynthesis
–  Contractile Vacuole: removes excess water
–  Cytoplasm
•  Food: They make their own food or absorb food
from their environment.
Euglena
•  Unicellular, eukaryotic, both Heterotrophic
and autotrophic
•  Moves- Flagella
•  Reproduces- fission (cell splits)
•  Eats- eyespot senses light to gather for
photosynthesis
Euglena
Amoeba
•  Environment: Mud at the bottom of freshwater ponds.
•  Movement: They change shapes which allows them to
move with their psuedopods.
•  Important Structures:
–  Cytoplasm: carries out chemical reactions
–  Nucleus: controls the cell
–  Cell Membrane: allows substances to enter and exit the
cell
–  Food Vacuole: digests food
–  Contractile Vacuole: gets rid of excess water
–  Pseudopodium: what allows it to move over mud (false
foot)
•  Capturing Prey: They surround their prey and engulf it.
Amoebas
• 
• 
• 
• 
Unicellular, Eukaryotic, heterotrophic
Moves-using Psuedopods
Reproduces- Binary fission
Eats-engulfing
Amoeba
Volvox
•  Environment: ponds, ditches, shallow
puddles
•  Movement: They beat cillia which allows it to
swim.
•  Important Structures:
–  Daughter colonies
–  Cillia: helps to move
–  Chloroplast: contains chlorophyll
•  Food: makes its own food by photosynthesis.
Volvox
• 
• 
• 
• 
Unicellular, eukaryotic, autotrophic
Moves- flagella
Reproduces- both sexually and asexually
Eats- by using the eye spot to sense light
so photosynthesis can occur.
Volvox
Paramecium
•  Environment: Fresh water or stagnant water
•  Movement: Cilia bend and straighten helping
propel the paramecium through water
•  Important Structures:
–  Contractile Vacuoles (2): removes excess water
–  Cytoplasm: water absorption
–  Cilia: hair-like projections that propel it through
water
–  Nucleus: controls cell activities
•  Food: uses cilia to sweep the food into the
cell.
Paramecium
• 
• 
• 
• 
Unicellular, eukaryotic, heterotrophic
Moves- cilia
Reproduces-sexually and asexually
Eats food from environment- through oral
grove, food vacuole, and anal pore.
Paramecium
• Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduc/on – Ex: bacteria
Cell Division—Mitosis Notes
Cell Division — process by which a cell divides into 2 new cells • Why do cells need to divide? 1. Living things grow by producing more cells, NOT because each cell increases in size
2. Repair of damaged Hssue
3. If cell gets too big, it cannot get enough nutrients into the cell and wastes out of the cell
• The original cell is called the parent cell; 2 new cells are called daughter cells
• Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of gene/c informa/on from parent cell
• Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell
2
Daughter
Cells
Parent Cell
DNA
• DNA is located in the nucleus and controls all cell ac/vi/es including cell division
• Long and thread-­‐like DNA in a non-­‐dividing cell is called chroma/n
• Doubled, coiled, short DNA in a dividing cell is called chromosome Consists of 2 parts: chroma/d and centromere
o 2 idenHcal “sister” chromaHds aVached at an area in the middle called a centromere o When cells divide, “sister” chroma/ds separate and 1 goes to each new cell
• ChromaHn to chromosomes illustraHon:
ChromaHn
Duplicates itself
Why does DNA need to change from chromaHn to chromosome?
Coils up into chromosomes
More efficient division
Mitosis – division of the nucleus into 2 nuclei, each with the same number of chromosomes • Mitosis occurs in all the soma/c (body) cells
So each new daughter cell Why does mitosis occur? has nucleus with a complete set of chromosomes
• 4 phases of nuclear division (mitosis), directed by the cell’s DNA (PMAT)
Prophase
Metaphase—(Middle)
Anaphase—(Apart)
Anaphase—(Apart)
Telophase—(Two)
Phase
Interphase
Prophase
Chromosome Appearance & Loca/on
DNA copies itself;
chromatin
Chromosomes coil up
Important Events
DNA replication, cell
grows and replicates
organelles
Nuclear envelope
disappears, spindle
fibers form
Chromosomes line up in
the middle
Spindle fibers connect
to chromosomes
Anaphase
Chromosome copies
divide and move apart
Telophase
Chromosomes uncoil
back into chromatin
Cytokinesis
Chromati
n
Spindle fibers pull
chromosome copies
apart to opposite poles
Nuclear envelopes
reform, 2 new nuclei are
formed, spindle fibers
Division of the rest of
disappear
the cell: cytoplasm and
organelles
Metaphase
SEXUAL REPRODUCTION
Sex cells formed by meiosis
Requires 2 parents
Offspring not identical
Meiosis
The process that results in the formation of gametes
Gametes
Sex cells, egg or sperm, which have haploid chromosomes
Haploid
Haploid means HALF, as in the number of chromosomes,
written as n
Fertilization
n
The union of an egg and a sperm
Zygote
n
2n
The cell that is formed when the egg becomes fertilized by the
sperm. This results in a full set of chromosomes.
Diploid
Diploid means they have chromosome found in pairs,
written as 2n
Homologous Chromosomes
Similar chromosomes that are found in pairs. The paired
chromosomes come from the mother and father.
* Human body cells have 46 chromosomes each
* Human body cells have 23 homologous pairs
Meiosis and Fertilization
Important for survival of many species, because these processes
result in genetic variation of offspring.
A kind of cell division that results in gametes (sex cells) with
half the number of chromosomes.
Meiosis Overview
•  Human body cells have 46
chromosomes.
•  Each parent contributes 23
chromosomes.
•  Takes place in sex cells (gametes):
egg and sperm
•  Delete the next line.