Video 2.1

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All living things contain a genome and a ribosome; showing common ancestry as all things are connected.

Ribosomes synthesize proteins according to mRNA sequences, and the instructions that are encoded into the mRNA sequence originate from the genome of the cell.

Ribosomes consist of two structures that are NOT membrane-concealed.

• Made of ribosomal (rRNA) and proteins

• Synthesize proteins according to mRNA sequences

The endoplasmic recticulum (ER) is a network of membrane tubes within the cytoplasm of eukaryotic cells. There are two forms of this: Rough ER and Smooth ER

1. Rough ER

   • Ribosomes attached to the membrane

   • Compartmentalizes the cell

   • Associating with packaging the newly synthesized proteins made by attached ribosomes for possible export from the cell.

2. Smooth ER

   • No ribosomes attached.

   • Functions involve detoxification and lipid synthesis.

   Structural differences between rough ER and smooth ER lead to functional differences.

Golgi Complex (Golgi Apparatus)

• Series of flattened membrane-bound sacs found in eukaryotic cells

• Involved in the correct folding and chemical modification of newly synthesized proteins and packaging for protein trafficking.

Mitochondria

• Has a double membrane

• Outer membrane is smooth and inner membrane is highly convoluted, forming folds called cristae

• Functions in production of ATP energy that eukaryotic cells use for cell work.

Lysosomes

• Membrane enclosed sacs found in some eukaryotic cells containing hydrolytic enzymes.

• Hydrolytic enzymes can be used to digest a variety of materials such as damaged cell parts or macromolecules.

Vacuoles

• Membrane-bound sacs found in eukaryotic cells

• Roles range from storage of water and other macromolecules to the release of waste from a cell.

Chloroplast

• Found in eukaryotic cells such as photosynthetic algae and plants.

• Double outer membranes

• Specialized for capturing energy from the Sun and producing sugar for the organism.

Textbook Reading (4.2)

Cytosol - semifluid, jelly-like substance where subcellular components are suspended.

Chromosomes - Carry genes in the form of DNA

Ribosomes - Tiny, complex, makes proteins

Eukaryotic Cells:

• Nucleus holds DNA, bonded by a double membrane

• Eukaryotic means “true nucleus”

• Larger than prokaryotic cells (10-100 um)

• Has cytoplasm holding organelles inside the cell.

Prokaryotic Cells:

• DNA in non-membrane enclosed region called the nucleoid

• Prokaryotic means “before nucleus”

• Do not contain organelles, however some regions of the cell are surrounded by proteins.

• Smaller than eukaryotic (1-5 um)

Mycoplasmas: Smallest cells known, a bacteria

Plasma Membrane: Selective barrier, allows passage of oxygen, nutrients and waste.

Biological Membranes: Double layer of phospholipids and other lipids.

• Formation of these leads to their specific function (Form leads to function)

As cell size increases, surface area grows proportionally less than its volume.

• Smaller object: Greater ratio of surface area; volume

Larger organisms doesn’t equal larger cells, generally it means more cells.

Video 2.2

Chloroplast are specialized for photosynthesis and capturing energy through the Sun to produce sugar, and have two departments.

1. Thylakoid

   • Highly organized membrane compartments (grana, organized in stacks)

   • Membrane contains chlorophyll pigments that comprise photostems

   • Electron transport proteins are found between photostems, embedded in the membrane.

   • Light-dependent reactions occur here.

   • Folding of internal membranes leads to increased efficiency of the reactions.

2. Stroma

   • Fluid between the inner chloroplast membrane and outside thylakoids.

   • Carbon fixation (Calvin-Benson cycle) reactions occur here.

Mitochondria

• Double membrane provides compartments for different metabolic reactions.

• Captures energy form macromolecules

• Krebs cycle (citric-acid cycle) reactions occur in the matrix.

• Electron transport and ATP synthesis occur in the inner mitochondrial membrane.

• Folding of the internal membrane increases the surface area, in turn creating more ATP.

Vacuoles

• Roles: Storage/Release of water, macromolecules, and cellular waste.

Hypotonic is when the solution has more solvent, less solute

• If a cell is in this type of solution, water will enter the cell, and the cell will expand/swell.

Hypertonic is when the solution contains higher levels of solute than solvent

• If a cell is placed in this type of solution, the water in the cell will leave and the cell will shrink.

Isotonic means solute and solvent concentrations are equal.