Download Nucleus - JeongAPbiology

Chapter 6
A Tour of the Cell
Things to Know
The differences between
eukaryotic and prokaryotic cells
The structure and function of
organelles common in plant and
animal cells
The structure and function of
organelles found only in plant or
animals cells
Prokaryotes vs. Eukaryotes
Characteristics
Prokaryotes
Eukaryotes
Plasma Membrane
Yes
Yes
Cytosol with organelles Yes
Yes
Ribosomes
Yes
Yes
Nucleus
No
Yes
Size
1-10 µm (micrometer)
10-100µm
Internal membranes
No
yes
• prokaryotes include domains Bacteria and Archaea
• eukaryotes belong to the domain Eukarya and
include animal, fungi, plants, and protists
Prokaryotes vs. Eukaryotes
• 3 things about Prokaryotes
- chromosomes are grouped in area called nucleoid
(no nucleus)
- no membrane-bound organelles (ribosomes are
present, but are not membrane bound)
- much smaller than Eukaryotes
• 3 things about Eukaryotes
- has membrane bound nucleus
- many membrane-bound organelles in cytoplasm
- average larger than Prokaryotes
Plasma Membrane
- the plasma membrane forms the boundary for
the cell
- Selectively permeable (allowing only some materials
in/out
- Made up of phospholipids; with proteins and carbs
throughout
- referred to as
“fluid mosaic”
model
Nucleus
• The nucleus contains the cell’s DNA
- Surrounded by a double membrane, nuclear envelope
- nuclear envelope contains
nuclear pores (holes) that
control enter and leaving nucleus
- chromatin is the DNA and
protein complex inside (used in
cell division)
- nucleolus is the region inside
where RNA is made
Ribosomes
• Ribosomes are sites of protein synthesis
- consist of large and small subunit
- may be free floating (when making proteins for the
cell or bound to endoplasmic reticulum (making proteins for
export)
Endoplasmic Reticulum
• the endoplasmic reticulum (ER) is a network of membranes
- smooth ER has 3 functions; synthesis of lipids,
metabolism of carbohydrates, and detox from drugs and
poisons
- rough ER has ribosomes
attached and are sites where
protein is made and distributed
to the golgi apparatus for export
Golgi Apparatus
• Proteins made by ribosomes on the ER are stored in
transport vescicles and shipped to the golgi apparatus.
• The golgi apparatus is the site where the proteins are
modified, stored, and shipped out of the cell
• Cisternae: flattened membranous sacs making up Golgi
• trans face (shipping)
& cis face (receiving)
Mitochondria
• Mitochondria is the site where cellular respiration occurs
• ATP is created from mitochondria, so it’s usually referred to
as the “powerhouse”
• Mitochondria are enclosed by
double membrane and has
inner membranes with folds
called cristae
Peroxisomes
• Peroxisomes are single-membrane bound
• Responsible for metabolic functions that involve
transferring hydrogen to oxygen (producing H2O2)
• Responsible for breaking down fatty acids to fuel the
mitochondria
Cytoskeleton
• Cytoskeleton is a network of fibers that run
throughout the cell for support, motility, and
regulating activities
3 types of fibers
- microtubules is made of protein and it’s the largest fiber
- microfilaments is composed of protein actin and it’s the
smallest fiber
- intermediate filaments are permanent medium sized
fibers
Centrosomes
• Centrosomes are regions located near the nucleus,
where microtubules grow
Found only in animal Cells
• Lysosomes contain enzymes that digest macromolecules
• Centrioles are located in centrosomes and are important in cell division
• 2 types of microtubles
-flagella is a long tail used to help cell propel through water (unicellular)
-cilia are “hairs” that also help cell move
• 3 types of intercellular junctions (connections to neihbor cells)
- tight junctions are when two cells are fused together making it watertight
- desmosomes fasten neighbor cells together, like nails
- gap junctions are channels or hole where the two neighboring cells
can exchange molecules
Found only in animal Cells
Extra Cellular Matrix (ECM)
-Glycoproteins - proteins covalently bonded to carbohydrate
-Collagen (50% of protein in human body); embedded in
proteoglycan (another glycoprotein-95% carbohydrate)
-Fibronectins - bind to
receptor proteins in plasma
membrane called integrins
(cell communication)
Found only in plant cells
• central vacuole are organelles that store and breakdown
some waste products. Plants have vacoule about 80% of
their size
• Chloroplast are in plant and algae cells and are the sites of
photosynthesis
• the cell wall protects and supports plant cells and are made
of cellulose
• Plasmodesmata are channels that allow plant cells to
exchange material with their neighbors