cells part 2. parts of the eukaryotic cell (organelles) nucleus cell membrane ribosome endoplasmic...
TRANSCRIPT
Cells Part 2
Parts of the Eukaryotic Cell(organelles)
Nucleus Cell membrane Ribosome Endoplasmic reticulum Mitochondria Cytoskeleton Vesicle
Nucleus: The Library
The nucleus stores all the cell's genetic information in massive molecules of DNA
The DNA molecules are packed into many pairs of chromosomes
When a protein is needed, signals enter the nucleus and cause copies of the appropriate genes to be made with RNA
Key Nucleus Facts:
Every complete human cell has one nucleus Exception: red blood cells have no nucleus (also
have no other membrane-bound organelles) Exception: muscle cells are many cell fused
together and so have many nuclei Every nucleus has the complete human genome The nucleus has its own envelope to keep
unwanted things out
Structure of DNA
Nucleic acid bases are attached to a special sugar and a phosphate to hold them in place
The four bases of DNA may be in any order and thus function as “letters” A matches T, C matches G
DNA to RNA to Protein Permanent information
is stored in DNA DNA information is
copied using RNA The information is for
protein sequences Alterations to the DNA
are faithfully copied and result in different protein sequences
This is mutation!
DNA to RNA The DNA sequence is copied onto a strand of
RNA in a process called transcription Referred to as messenger RNA or mRNA
Technically must be processed first to be mRNA
Ribosome: The Machine Shop
Site of protein synthesis Proteins perform major cell
functions, including making up the cytoskeleton
Made with a combination of protein and RNA Probably the first structure in
the original cells
Key Ribosome Facts Ribosome is the site for proteins to be synthesized,
called translation Molecules called tRNA attach the amino acids together
using the ribosome as the workbench Cytoplasmic ribosomes make the cytoskeleton and cell
enzymes (proteins that stay in the cell) The endoplasmic reticulum is a membrane-bound
organelle that uses ribosomes to make cell structures and secretions
Protein synthesis is essential for all cells to stay alive This is why ribosomal inhibitors like ricin are lethal poisons
Mitochondria: The Power Plant• Mitochondria (singular:
mitochondrion) produce the cell's supply of energy molecules– Cells use a molecule called ATP– Made using the energy from
blood sugar
• Must have oxygen to work– Process that requires oxygen is
called aerobic
Key Mitochondria Facts: Mitochondria were once bacteria
Captured/adopted by animal cells billions of years ago and now we work together
Mitochondria must have oxygen to burn sugar Produce CO2 as a waste product This is why we breathe in oxygen and breathe
out carbon dioxide Mitochondria sustain our high metabolic rate
Cyanide blocks mitochondrial activity, which is why it is a lethal poison to us
Mitochondria Activity
• Mitochondria perform aerobic respiration (requiring O2)
• Prokaryotes have no membrane-bound organelles, therefore they do not have mitochondria– Some bacteria are aerobic, which means they
perform the same processes as a mitochondrion!
Cytoskeleton: The City Streets Every cell has long
strands of proteins running through it
When organelles are moved they move along the cytoskeleton If the cell moves under its
own power it uses the cytoskeleton as well
Key Cytoskeleton Facts: There are several different types of fibers and
they have different functions All cells must produce each of these fibers
These fibers are made of different kinds of proteins (keratin, collagen, actin, myosin, etc) If the genes for any of these fibers are no good, no
cells can form and the organism will never develop, grow or be born
This makes these genes essential for life
Cytoplasm: The Marketplace The liquid of the cell is called
cytosol Cytosol plus the organelles are
called cytoplasm All the cell's chemical
reactions and growth take place here Enzymes are proteins designed
to speed up chemical reactions Vesicles are storage organelles
that are kept in the cytoplasm