DNA Transcription

DNA -> RNA the process of copying DNA into RNA using RNA polymerase

DNA Translation

RNA -> Protein the process of decoding mRNA into a protein using ribosomes, tRNA, and amino acids.

Central dogma of cell bio

DNA -> RNA -> Protein

Cell theory

1. All living things are made up of cells - despite diversity 2. All living cells are similar in structure and function 3. All cells arise from pre-existing cells - spontaneous generation doesn't occur

Four universal functions of cell

1. Selective barrier 2. Inherit and transmit genetic material 3. Metabolism 4. Motility

2 ways to visualize cells (microscopy)

Light microscopy and electron microscopy

Light microscopy

Visualization of samples using light • Magnifies samples to ~1000X • Manipulation of contrast and labelling methods help visualize cell components to achieve higher resolution • Still, most organelles are too small to visualize using standard light microscopy • Many variations on light microscopy exist - Can look at LIVING cells

Limitations of light microscopy

• Visualization of very small samples not possible (or at least, very difficult) due to loss of resolution • Physical limitation due to diffraction of light • Wavelength of light is too long! • Solution: Electron microscopy!

Electron microscopy

Uses beams of electrons to see finer details since electrons have much shorter wavelength than visible light • Resolution of ~0.1 nm vs. 200 nm for light microscopes - Can't look at living cells

2 types of electron microscopy

#NAME?

TEM

Transmission electron microscopy used to visualize the internal structures • In principle, similar to light microscopy • Super-thin samples prepared • Beam of electrons pass through the sample • Electrons interact with the sample • Image produced • Creates a sectional view (looks 2D)

SEM

Scanning electron microscopy used to visualize the surfaces of samples • Samples coated in conductive material (gold, platinum, etc.) • Electrons focused on surface • Excites atoms, which emits secondary electrons • Secondary electrons detected to create image • Creates a surface-level view (looks 3D)

2 types of cells

Prokaryotic and Eukaryotic

Eukaryotic cells what they are and their cell components

Protists, fungi, plants and animals are eukaryotes • DNA in a nucleus • Membranous nuclear envelope • Membrane-bound organelles • Compartmentalization of function • Cytoplasm between plasma membrane and nucleus • Eukaryotic cells are generally much larger than prokaryotic cells - Have linear DNA - More than 1 chromosome - Divide via mitosis (budding or fission) - Have mitochondria - Have chloroplasts (plants & algae)

Prokaryotic cells what they are and their cell components

Archaea and bacteria are prokaryotes -DNA in an unbound region called nucleoid (no nucleus!) • No membrane-bound organelles • All components in cytoplasm • Small • Extremely diverse in shape • More numerous and diverse than eukaryotic cells - Have cell wall - Circular DNA -Single chromosome -Divide via binary fission

4 Features of all cells (prokaryote and eukaryote similarities)

Eukaryotic and prokaryotic cells both have: • Plasma membrane • Semifluid substance called cytosol • Chromosomes (carry genes) • Ribosomes (make proteins)

Cytoplasm vs Cytosol definitions

• Cytoplasm = everything in between the plasma membrane and nuclear envelope • Cytosol = cytoplasm without everything (i.e. organelles) in it

Ribosomes

• Ribosomes = ribosomal RNA + protein • Ribosomes carry out protein synthesis in two different locations: • In the cytosol (free cytosolic ribosomes) • On the surface of the endoplasmic reticulum (ER-bound ribosomes)

Endomembrane system

• A group of membranes (in turn, organelles) that compartmentalize the cell • Endo- = inner, within • Regulates protein traffic and performs metabolic functions in the cell • Components of endomembrane system • Nuclear envelope • Endoplasmic reticulum • Golgi apparatus • Lysosomes • Vacuoles • Plasma membrane • These components are either continuous or connected indirectly via vesicles ( review physical flashcards for functions of each organelle in the endomembrane system)

Endocytosis

The cell engulfs extracellular materials in vesicles that can't cross the membrane directly - Active transport (requires ATP)

Exocytosis

The cell exports materials that can't cross the membrane directly by fusing vesicles with the plasma membrane to release materials outside the cell - Active transport (requires ATP)

Endosymbiosis

The theory that explains the origin of mitochondria and chloroplasts. Mitochondria and chloroplasts originated from formerly free-living bacteria. These bacteria became established inside an ancestral host cell for the invading mitochondria and chloroplast. During evolutionary time, they became integrated with the host cell and developed into cellular organelles.

Evidence for endosymbiosis theory

Mitochondria and chloroplasts are similar to bacteria because: - Both divide by binary fission - Contain their own circular DNA - Have own ribosomes - Double membrane Leading scientists to believe that they originated from prokaryotes

Cytoskeleton roles and types

• A network of fibres extending throughout cytoplasm • Two main roles: 1. Support 2. Motility Types: Actin Microtubules Intermediate filaments ( review physical cards from 111)