Cell_Structure_and_Function-HonorsPhysio corrected

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Transcript Cell_Structure_and_Function-HonorsPhysio corrected

Name that Organelle!
Golgi Complex
Rough ER
Smooth ER
Cell Membrane
Cell Wall
What does the cell theory tell us?
• A cell is the basic unit of life
• All living things are made up of cells
• New cells arise from preexisting cells
Why are most cells small?
• Consider the cell surface-area-to-volume
– Small cells have a larger amount of surface
area compared to the volume
– An increase in surface area allows for more
nutrients to pass into the cell and wastes to
exit the cell more efficiently
– There is a limit to how large a cell can be and
be an efficient and metabolically active cell
Thinking about surface area to volume
in a cell
In Your Notes
• Using progessively larger cubes as a
representation for cells, explain why cells
must stay small to be able to provide for
What are the two major types of
cells in all living organisms?
• Prokaryotic cells
– Thought to be the first cells to evolve
– Lack a nucleus
– Represented by bacteria and archaea
• Eukaryotic cells
– Have a nucleus that houses DNA
– Many membrane-bound organelles
What do prokaryotic and eukaryotic
cell have in common?
• A plasma membrane that surrounds and
delineates the cell
• A cytoplasm that is the semi-fluid portion
inside the cell that contains organelles
What do eukaryotic cells look like?
What are some characteristics of
the plasma membrane?
• It is a phospholipid bilayer
• It is embedded with
proteins that move in
• It contains cholesterol for
• It contains carbohydrates
on proteins and lipids
• Selectively permeable
What does selectively permeable
• The membrane allows
some things in while
keeping other
substances out
In your Notes!
• https://www.youtube.com/watch?v=S7CJ7
• Explain how the cell membrane is like a
screen door.—you may want to expand
the analogy to make it more complete.
How do things move across the
plasma membrane?
Facilitated transport
Active transport
Endocytosis and exocytosis
What are diffusion and osmosis?
• 1. Diffusion is the
random movement of
molecules from a
higher concentration
to a lower
• 2. Osmosis is the
diffusion of water
How does tonicity change a cell?
• Hypertonic solutions have
more solute than the inside
of the cell and lead to
crenation (crenation)
• Hypotonic solutions have less
solute than the inside of the
cell and lead to lysis (bursting)
• Isotonic solutions have equal
amounts of solute inside and
outside the cell and thus does
not affect the cell
In Your Notes
• Explain why saline IVs must be isotonic to blood
in order to be effective. Be sure to use
crenation and lysis in your explanation.
What are endocytosis and
• 5. Endocytosis transports
molecules or cells into the
cell via invagination of the
plasma membrane to
form a vesicle
• 6. Exocytosis transports
molecules outside the cell
via fusion of a vesicle
with the plasma
What must DNA do?
1. Replicate to be passed on to the next
2. Store information
3. Undergo mutations to provide genetic diversity
DNA structure: A review
Double-stranded helix
Composed of repeating nucleotides (made of a
pentose sugar, phosphate and a nitrogenous base)
Sugar and phosphate make up the backbone while
the bases make up the “rungs” of the ladder
Bases have complementary pairing with cytosine (C)
pairs with guanine (G) and adenine (A) pairs with
thymine (T)
DNA structure
How does DNA replicate?
The two strands unwind by
breaking the H bonds
Complementary nucleotides
are added to each strand by
DNA polymerase
Each new double-stranded
helix is made of one new
strand and one old strand
(semiconservative replication)
The sequence of bases
makes each individual unique
DNA replication
Check out the Animation!
• http://www.dnai.org/a/index.html
RNA structure and function
Composed of repeating nucleotides
Sugar-phosphate backbone
Bases are A, C, G and uracil (U)
Three types of RNA
– Ribosomal (rRNA): joins with proteins to form ribosomes
– Messenger (mRNA): carries genetic information from DNA to
the ribosomes
– Transfer (tRNA): transfers amino acids to a ribosome where
they are added to a forming protein
RNA structure
Sum It Up!!!
• Make a Venn Diagram in your notes to
compare and contrast DNA and RNA.
Comparing DNA and RNA
• Similarities:
– Are nucleic acids
– Are made of
– Have sugar-phosphate
– Are found in the
• Differences:
– DNA is double
stranded while RNA is
single stranded
– DNA has T while RNA
has U
– RNA is also found in
the cytoplasm as well
as the nucleus while
DNA is not
Proteins: A review
Composed of subunits of amino acids
Sequence of amino acids determines the shape of the
Synthesized at the ribosomes
Important for diverse functions in the body including
hormones, enzymes and transport
Can denature causing a loss of function
Proteins: A review of structure
2 steps of gene expression
1. Transcription – DNA
is read to make a
mRNA in the
nucleus of our cells
2. Translation –
Reading the mRNA
to make a protein in
the cytoplasm
Check out the Animation!
• http://www.dnai.org/a/index.html
Overview of transcription and translation
Check out the Animation!
• http://www.dnai.org/a/index.html
The genetic code
Made of 4 bases
Bases act as a code for
amino acids in
Every 3 bases on the
mRNA is called a
codon that codes for a
particular amino acid in
What did we learn from the human
genome project (HGP)?
Humans consist of about 3 billion bases and
25,000 genes
Human genome sequenced in 2003
There are many polymorphisms or small
regions of DNA that vary among individuals
were identified
Genome size is not correlated with the number
of genes or complexity of the organisms
DNA technology terms
• Genetic engineering – altering DNA in bacteria, viruses,
plants and animal cells through recombinant DNA
• Recombinant DNA – contains DNA from 2 or more
different sources
• Transgenic organisms – organisms that have a foreign
gene inserted into them
• Biotechnology – using natural biological systems to
create a product or to achieve an end desired by
In Your Notes
• Explain the two steps of protein synthesis,
starting with transcription in the nucleus
and then translation at the ribosome.
What is the cytoskeleton?
• A series of proteins that maintain cell
shape as well as anchors and/or moves
organelles in the cell
• Made of 3 fibers: large microtubules, thin
actin filaments and medium-sized
intermediate filaments
What are cilia and flagella?
• Both are made of
• Both are used in
• Cilia are about 20x
shorter than flagella
What do mitochondria do and what do
they look like?
• A highly folded
organelle in
eukaryotic cells
• Produces energy in
the form of ATP
• They are thought to
be derived from an
engulfed prokaryotic
Enzymes are important for cellular
respiration and many activities in the cell
• Most enzymes are proteins
• Enzymes are often named for the molecule that
they work on or substrates
• Enzymes are specific to what substrate they
work on
• Enzymes have active sites where a substrate
• Enzymes are not used up in a reaction but
instead are recycled
• Some enzymes are aided by non-protein
molecules called coenzymes
How do enzymes work?
What is cellular respiration?
Production of ATP
in a cell
1. Glycolysis
2. Citric acid cycle
3. Electron transport
What happens in glycolysis – step 1 of
cellular respiration?
• Glycolysis
– Occurs in the cytoplasm
– Breaks glucose into 2 pyruvate
– NADH and 2 ATP molecules are made
– Does not require oxygen
What happens in glycolysis – step 2 of
cellular respiration?
• Citric acid cycle
– A cyclical pathway that occurs in the
– Produces NADH and 2 ATP
– Requires oxygen
What happens in glycolysis – step 3 of
cellular respiration?
• Electron transport chain
– Series of molecules embedded in the
mitochondrial membrane
– NADH made in steps 1 and 2 carry electrons
– 32-34 ATP are made depending on the cell
– Requires oxygen as the final electron
acceptor in the chain
What other molecules besides glucose
can be used in cellular respiration?
• Other carbohydrates
• Proteins
• Lipids
How can a cell make ATP without oxygen?
• Fermentation
– Occurs in the cytoplasm
– Does not require oxygen
– Involves glycolysis
– Makes 2 ATP and lactate in human cells
– Is important in humans for a burst of energy
for a short time