bio 1111 exam 2 cells

cells

  • fundamental units of life

  • 3 tenets of the cell theory

    • cells are the simplest unit that can carry out all functions of life

    • all living things are composed of one or more cells

      • organismal functions have basis in cell function

    • new cells are created by previous cells

electron microscopes

  • observing smallest structures

    • transmission electron microscope (TEM)

      • observe the electrons that can pass through a thin specimen

    • scanning electron microscope (SEM)

      • observe the electrons that scatter off a specimen to get a 3D-like image

living organisms exhibit simultaneous unity and diversity

  • life on earth is divided into 3 major groups (domains)

    • eubacteria

    • archaea

    • eukarya

cell characteristics- all living things

  • cell (plasma) membrane

    • phospholipid bilayer

    • selective barrier

    • encloses cytoplasm (main compartment of cell)

  • biological molecules

    • carbohydrates

    • lipids

    • proteins

    • nucleic acids (DNA/RNA)

2 related, classes of cells

prokaryotic cell (bacterium)

  • “before nucleus”

  • domains

    • archaea and eubacteria

  • smaller (1-5μM)

  • DNA stored in cytoplasm

  • only single-celled organisms

eukaryotic cell (amoeba)

  • “true nucleus”

  • domain

    • eukarya

  • DNA stored in nucleus (surrounded by membrane)

  • organelles (”little organs”) surrounded by membranes with specialized jobs

  • larger (10-100μM), have internal compartments

  • single and multicelled organisms

metabolism imposes theoretical limits on cell size

  • cube

    • surface area (SA)→ Height x Width x # of Sides

    • volume (V)→ Height x Width x Length

    • smaller objects= larger SA:V ratio

  • metabolic reactants (food) and products (waste) must diffuse across the cell membrane

  • high SA:V ratio required for sufficient exchange

eukaryotic cell organelles

  • eukaryotic organelles are specialized to different cellular tasks

  • some parts of your body need more of certain organelles than others because those cells are specialized to those tasks

mitochondria

  • site of most energy production in cell respiration

  • found in all eukaryotic cells, but cells with higher energy demand have more

lysosome

  • immune cells use lysosomes to digest pathogens they consume

  • digests objects brought into the cell by endocytosis

    • using cell membrane to surround/ingest another cell/food/protein

  • found in most animal cells, but more found in endocytic cells like immune cells

smooth endoplasmic reticulum (SER)

  • the liver uses this and peroxisomes to remove toxins/manage fat metabolism

  • contains enzymes for destroying toxins

  • where phospholipids are made

peroxisome

  • manages hydrogen peroxide levels

  • regulates fat metabolism

rough endoplasmic reticulum (RER)

  • rough due to it being covered in protein-making factories (ribosomes)

  • site of protein synthesis for proteins that will be released to outside cells

  • pancreas uses this and golgi apparatus to produce/release protein enzymes and hormones for digestion

golgi apparatus

  • sorts, modifies, and ships proteins meant for release to outside of cell

  • ex. creating glycoproteins

vesicle

  • small sack surrounded by membrane used to move things between organelles

cytoskeleton

  • organizes cellular structures/activities

  • dynamic network of fibrous proteins throughout the cytoplasm

  • 3 major fiber types

    • microtubules

    • microfilaments (actin)

    • intermediate filaments

  • provide cell with shape/rigidity and help attach cell to neighboring cells/surroundings

  • movement of vesicles, organelles, chromosomes during mitosis, cells, and muscles