BIO 12: CELLS 𓂃⋆.˚

Cell

Latin: cellae

- Is a fundamental unit of life

- All organisms consist of one or more microscopic structures

1660

- Where the study of cells began

Robert Hooke

- He melted strands of spun glass to created lenses and used it to look at a cork - left by cells that were once alive

- English physicist

Cell Theory

- Mathias J. Schleidan and Theodor Schwann observed many different plants and cells and formulated:

1.) All organisms are made of one cells or more cells

2.) Cells are the fundamental unit of all life

Rudolf Virchow

- Proposed all cells came from preexisting cells

Prokaryotic Cells

- Only organisms of the domains Bacteria and Archaea

- Simple-celled

- No nucleus

- DNA in an unbound region called the nucleoid

- No membrane-bound organelles

- Cytoplasm bound by the plasma membrane

Eukaryotic Cells

- Protists, Fungi, Animals, and Plants

- Generally much larger

- DNA in nucleus that is bounded by a membranous nuclear envelope

- Membrane-bound organelles

- Cytoplasm in the region between the plasma membrane and nucleus

Pro/a

- meaning "before" or "no"

Eu

- meaning "true"

- Plasma membrane

- Semifluid substance called Cytosol

- Chromosomes(carries genes)

- Ribosomes (make proteins)

Basic features of all cells

Plasma Membrane

- A selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

Double layer of phospholipids

The general structure of a biological membrane

Apoptosis

- Programmed cell death

Nucleus

- Contains most of the DNA in a eukaryotic cell

- Contains most of all the cell's genes and is usually the most conspicuous organelle

- Contains karyoplasm

- The shape is maintained by the nuclear laminas which is composed of protein

Nuclear Envelope

- Encloses the nucleus, separating it from the cytoplasm

Nuclear Membrane

- A double membrane

- Each membrane consists of a lipid bilayer

Pores

- Regulate entry and exits of molecules from the nucleus

Chromatin

- Condenses to form discrete chromosomes

- DNA and proteins form genetic material

Nucleolus

- Located within the nucleus and is the site of ribosomal(rRNA) synthesis

Ribosomes

- Particles made of ribosomal RNA and protein

- Carry out protein synthesis in two locations: In the cytosol(free ribosome), and on the outside of the ER or nuclear envelope(bound ribosome)

Smooth Endoplasmic Reticulum (Smooth ER)

- Synthesizes lipids

- Metabolizes carbohydrates

- Detoxifies poison

- Stores calcium

- Lacks ribosomes

Rough Endoplasmic Reticulum (Rough ER)

- Has bound ribosomes

- Secretes glycoproteins (bonded to carbohydrates covalently)

- Membrane factory of the cell ribosomes

- Distributes transport vesicles, proteins by the cell

Golgi Apparatus

- Modifies products of the endoplasmic reticulum

- Sorts and packages materials into transport vesicles

Lysosomes

- Membranous sac of hydrolytic enzymes that can digest macromolecules

Lysosomal Enzymes

- Hydrolytic proteins, fats, and nucleic acids

Mitochondria

- Are the cites of cellular respiration, a metabolic process that generates ATP

- Powerhouse of the cell

Adenosine Triphosphate (ATP)

- Energy currency of the cell

Chloroplasts

- Site of photosynthesis

- Found in plants and algae

- Animal cells don't have these

Peroxisomes

- Oxidative organelles

Mitochondria and Chloroplasts

- Are not part of the endomembrane system

- Have a double membrane

- Have proteins made by free ribosomes

- Contain their own DNA

Chemical Energy Conversion

- Mitochondria are in nearly all eukaryotic cells, they have a smoother outer membrane than an inner membrane folded into "cristae"

1. Intermembrane Space

2. Mitochondrial Matrix

Inner membrane creates to compartments:

Mitochondrial Matrix

- Some metabolic steps of cellular respiration are catalyzed

Intermembrane Space

- Space between inner and outer mitochondrial membranes

Cristae

- Present a large surface area for enzymes that synthesize ATP

Peroxisomes Oxidation

- Specialized metabolic compartments bounded by a single membrane

- Produce hydrogen peroxide and connect it to water

- Oxygen is used to break down different types of molecules

Thylakoid

- Photosynthetic reactions

Cytoskeleton

- A network of fibers extending throughout the cytoplasm

- Organizes the cell's structures and activities, anchoring many organelles

- Helps support cell to maintain shape

- Interacts with proteins to produce mobility

- May regulate biochemical activities

1. Microtubules

2. Microfilaments

3. Intermediate Filaments

Cytoskeleton is composed of three types of molecular structures:

Microtubules

- Thickest

- Grow out from a centrosome near the nucleus

Microfilaments

- Also called the actin filaments

- Thinnest components

Intermediate Filaments

- Fibers with diameters in a middle range

Centrosome

- "Microtubule-organizing center"

- In animal cells, it has a pair of centrioles, each with nine triplets of microtubules arranged in a ring

Centrioles

- Cell organelle that aids in cell division in animal cells only

Vacuoles

- Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Flagella

- Tail-like appendages that enable prokaryotic cells to move

Cell Wall

- Usually rod-shaped, round, or spiral

- Surrounds the cell membrane of most bacteria, protecting the cell and preventing it from bursting if it absorbs too much water

- Gives shape