Unit #1 Cells

Cell theory: 1. Every living thing is made up of one or more cells and their products

2. Cells are the simplest unit that carry out all life processes.

3. All cells come from pre-existing cells. They do not come from non-living matter.

Simplest Organisms: Archaea and Bacteria (prokaryotes)

Prokaryotes:

• No nucleus

• No membrane bound organelles

• (capsule, plasmid, flagellum, pilus)

Eukaryotes :

• Complex cells

• Can exist as single celled organisms or multicellular organisms

• have complex internal organization/components

• 10 - 1000 x bigger than prokaryotes

• Have nucleus

• protists, fungi, animals, plants

Cell Structure:

Cell wall:

• multilayered (3)

• support and protect the cell

• controls the direction of cell growth

• selective transportation

• Plants only

Cell membrane:

• Fluid-mosaic membrane

• separates the cell interior from outside

• controls movement in and out of cell

• Both plants and animals

Cytoplasm:

• consists of mostly water and dissolved materials

• creates chemical environment where the other cells work

• Both

Vacuoles:

• fluid filled sac

• temp. storage of food water, or waste products

• Both (big in plants, small in animals)

Nucleus

• contains DNA

• double membrane

• control center of cell

• contains DNA blueprints for making proteins

• Both

Chromosomes:

• located inside nucleus (microscopic)

• carries hereditary info. (genes)

• helps organize genetic material during cell division

• Both

Endoplasmic Reticulum:

• flattened membrane-bound sacs and tubes

• Rough ER is studded with ribosomes

• Rough ER: synthesizes protein

• Smooth ER: synthesizes phospholipids and packages macro molecules in vesicles to transport to other parts of cell

• Both

Golgi Apparatus:

• stack of flattened membrane bound sacs that contain enzymes

• receive vesicles from ER

• contains enzymes for modifiying protein and lipids

• sends finished product to vesicles to go to cell membrane

• Both

Mitochondria:

• double membrane system & has own DNA

• powerhouse of cell

• generates energy (atp)

• signals between cells & cell death

• heat production

• stores calcium

• Both

Chloroplast:

• type of plastid & has double membrane

• photosynthesis

• Plants only

Ribosomes:

• half protein half RNA

• produce proteins from amino acid (protein synthesis)

• Both

Lysosomes:

• contains digestive enzymes

• breaks down cellular wastes and debris

• can kill other cells

• helps maintain homeostasis

• Animals only

Chromatin:

• mix of DNA, RNA, and proteins that form chromosomes

• condense and package DNA

• Both

Nucleolus:

• found in cells nucleus (sphere)

• produce and assemble ribosomes

• RNA

• Both

Transport in Cells:

Homeostasis - the state of steady internal, physical, and chemical conditions maintained by living systems

Passive Transport: 1. Diffusion -movements of a molecule from a region where they are more concentrated to one where they are less

2. Osmosis - the diffusion of water molecules across a semi-permeable membrane down a concentration gradient

3. Facilitated Diffusion -diffusion through a carrier/channel protein molecule

Carrier Protein: will accept only a non-charged molecule with a specific shape

Channel Protein: allows charged particles (must be small and have the right charge)

Active Transport: 1. Active transport pump - the process of moving substances against a concentration gradient

2. Bulk Transport -mode of transport of large quantities of materials and food particles across the membrane. Occurs inward and outward.

Phagocytosis: ingest or engulf other cells or particles

Endocytosis: Ingestion of large particles (bacteria) and the uptake of fluids or macromolecules in small vesicles

Exocytosis/ectocytosis: Fusion of secretory vesicles with the plasma membrane and results in the discharge of vesicle content into the extracellular space

Pinocytosis: Active, energy consuming process where extracellular fluid and solutes are taken up into a cell via small vesicles

Isotonic: equal concentration of solutes inside and outside the cell. Cell is the same.

Hypotonic: Less solute in the solution than in the cell. Cell is Lysed (bigger).

Hypertonic: Higher concentration of solute (ex. cell expands and dies due to lysis)

Cell cycle:

• interphase (every phase except m phase): -resting phase - cell grows and prepares for cell division by duplication of genetic material

• cytokynesis: cycle begins

• G1 phase: cell grows

• S phase: cells recieves instructions regarding divisions, Dna replicates

• G2 phase: cell prepares to divide

• M phase (mitosis)

Bacteria:

• contains ribosomes, cytoplasm, chromatin/chromosomes (nucleoid), Flagellum, capsule, plasma membrane, pilus

Naming Bacteria:

• rod shaped bacteria is called bacillus (bacilli)

• sphere shaped bacteria is called coccus (cocci)

• spirochete shaped bacteria is called spirillium (spirillia)

• bacteria in pairs are diplo

• bacteria in chains are strepto

• bacteria in clusters are called staphylo

Bacteria Reproduction:

• binary fission

  1. single circular chromosome consists only of double stranded DNA

  2. Chromosome duplicates, the two chromosomes attach to the inside of the cell membrane

  3. cell produces division furrow which is the beginning of a septum. (eventually will turn into a cell wall.

  4. cell membrane grows inward and the cell wall completely forms.

  5. original cell splits into two smaller genetically identical cells.

Conjugation:

• genetic recombination

  1. recipient cell connects to donor cell using a conjugation tube (pilus)

  2. makes a copy of some of the donor cells DNA (plasmid)

  3. Plasmid makes its way to recipient cell through pilus

Viruses:

• do not contain cells or any cellular structure

• not considered organisms

• non-living

• composed of a protective coat of protein called a capsid and DNA or RNA

• DNA or RNA is used to rewrite the host cells genome and produce more viruses

Lytic cycle:

1. Attachment: -virus lands on host cell

2. Entry: -RNA or DNA enters the host cell and become part of the host cell’s genome

3. Replication: -hijacked host cell creates new viral parts

4. Assembly: -viral parts are assembled

5. Lysis: -manufactured viruses bursts out of host cell, causing the host cell to die