Name that Organelle! Mitochondria Chloroplasts Nucleus Lysosome Golgi Complex Ribosomes Rough ER Smooth ER Nucleolus Cell Membrane Cell Wall Cytoplasm Vacuole

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 ratio: –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 themselves.

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 DNA

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 space It contains cholesterol for support It contains carbohydrates on proteins and lipids Selectively permeable

What does selectively permeable mean? The membrane allows some things in while keeping other substances out

In your Notes! xZOjm0https:// xZOjm0 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? 1. Diffusion 2. Osmosis 3. Facilitated transport 4. Active transport 5. Endocytosis and exocytosis

What are diffusion and osmosis? 1. Diffusion is the random movement of molecules from a higher concentration to a lower concentration 2. Osmosis is the diffusion of water molecules

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 exocytosis? 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 membrane

What must DNA do? 1.Replicate to be passed on to the next generation 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

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RNA structure and function Single-stranded 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 nucleotides –Have sugar-phosphate backbones –Are found in the nucleus 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 protein 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

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Overview of transcription and translation Bio

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The genetic code Made of 4 bases Bases act as a code for amino acids in translation Every 3 bases on the mRNA is called a codon that codes for a particular amino acid in translation

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 techonology 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 humans

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 microtubules Both are used in movement 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 cell

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 binds 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 Includes: 1.Glycolysis 2.Citric acid cycle 3. Electron transport chain

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 mitochondria –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 here –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