L2: Eukaryotic Cells, Basic chemistry

eukaryotic cells

Cells that contain a nucleus and membrane-bound organelles, distinguishing them from prokaryotic cells.

• internal organelles increase effective surface area to volume ratio

• compartmentalization of functions in specific organelles allows efficient regulation

nucleus

houses hereditary material

• ribosomal subunits are manufactured in the nucleus and is the control center of the cell.

Structural features of the nucleus (4)

1. Nuclear envelope

2. Nuclear lamins

3. Nuclear pore complex

4. Nucleolus

Nuclear envelop

dual bilayer membrane

• lumen (inside of the organelle) between bilayers is continuous with the lumen of the ER

nuclear lamins

cytoskeleton structure that supports the nuclear envelope

nuclear pore complex

specialized structures for transport across nuclear envelope

• exist on the nucleus, highly regulated, and allow molecules to go inside and out the nucleus

nucleolus

area in the nucleus where ribosomal RNA is synthesized and ribosomes are constructed

• non-membrane bound

• high concentration of ribosomal material

endoplasmic reticulum (EM)

extensive interconnected network of membrane bound structured with the primary jobs of protein synthesis and lipid synthesis

• lumen of the ER is continuous w/ the lumen of the nuclear envelope

• connected to other membrane bound organelles by vesicles

Jobs of the ER (5)

1. protein synthesis

2. translation

3. folding

4. processing of proteins bound for membrane-bound compartments for the outside of the cell

5. lipid synthesis

rough ER

involved in protein synthesis

• covered by ribosomes

smooth ER

involved in lipid synthesis

Golgi apparatus

organelle where proteins are modified for further function and transport

• sugars are also added to proteins here

• connected to other organelles and the plasma membrane via membrane-bound vesicles

secretory vesicles

vesicles going TO the plasma membrane

endocytic vesicles

vesicles going FROM the plasma membrane to other organelles

lysosomes

used for the degradation of macromolecules

• semi-stable membrane bound organelles located between the Golgi and plasma membrane

• contain hydrolytic enzymes that work at low pH

endomembrane system (7 steps)

1. Protein synthesis

   1. mRNA leaves the nucleus and directs ribosomes to assemble proteins from amino acids

2. Proteins enter the ER

3. Vesicle transport to ER

   1. Carry unfinished proteins/lipids

4. Processing in the Golgi complex

5. Vesicle movement in the Golgi

   1. Vescicles transport modifying enzymes within the Golgi for further processing

6. Secretion and Plasma Membrane Transport

   1. Soluble proteins are released via exocytosis

7. Lysosome Formation & Waste breakdown

   1. Break down damaged organelles and endocytic vesicle content

mitochondria

cell respiration

• generation of ATP from the breakdown of macromolecules

micro bodies

lipid breakdown and other metabolic processes

• ex. peroxisomes

list of plastids (3; plants)

1. chloroplast: metabolic organelles where photosynthesis occurs

2. amyloplasts: starch storage

3. chromoplasts: pigment storage

ONLY IN PLANTS

central vacuole (plants)

membrane bound fluid filled sac that provides structural support

ONLY IN PLANTS

cell wall (plants)

extracellular structure made of cellulose that provides structure and protection

• has a primary and secondary version

• located outside the plasma membrane

• contains a lamella: polysaccharide layer between cells

• contains plasmodesmata: channels between cells that cross cell walls to allow material exchange

endosymbiont theory

mitochondria and chloroplasts originated as free-living bacteria that were engulfed by ancestral archaen eukaryotic cells.

• highlights the symbiotic relationship formed between these bacteria and their host cells, leading to the evolution of complex eukaryotic life.

• eventually evolved together

inside-out theory

archean species formed symbiotic relationship with bacterial cell and exchanged nutrients

• Archean cell extended its membrane outside to form close association with bacteria

• Over time, these outward projections surrounded bacterial partners, eventually enclosing them within host cell becoming mitochondria, etc.

• Evolved to get better surface area to exchange nutrients better

elements

pure substance that cannot be broken down into simpler substances by normal chemical/physical techniques

• unit of an element is the atom

• most concerned with carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (for living things)

• organized into groups based on valence electrons

periods

elements with the same number of electron shells

molecules

atoms can combine through chemical bonds to form molecules

• only the same element

• Ex. O2

compounds

molecules that are formed from atoms of different elements

• Ex. H2O

Atomic nucleus

inner core of an atom

• contains protons and neutrons

• electron shell is the orbit of electrons around the nucleus

protons

subatomic particle with positive charge

• number of protons in the nucleus is called the atomic number

  • uniquely defines the atom of a given element

neutrons

subatomic particles with no charge

• usually exist in equal number with protons in the nucleus

• # of protons + # of neutrons give the atomic mass

• protons and neutrons are held together by a strong force called the nuclear force

electrons

negatively charged subatomic particles that occupy 99.9% of an atoms space

• only account for 0.01% of atoms mass

shells

the orbit that a given electron takes around the nucleus

• electrons are organized into shells

valence electrons

electrons in the most outer shell

• the number of electrons in the outer shell determines the reactivity of an element