BIOL 102 Week 2 Cells

Key idea

Structure indicates function

Microscopy

One way to study cells with lots of different types

Light microscopy

Beam of light passes through a specimen and allows us to see living cells & movement

Electron microscopy

Beam of electrons passes through specimen allowing you to see smaller scale but too destructive for live specimens

Cytoplasm

Cell interior containing organelles (excluding the nucleus) AND cytosol

Cytosol

Strictly the cellular fluid

Ribosome structure

Non-organelles made of RNA and protein, made of large and small subunit, can either be free or bound to ER/nuclear envelope

Ribosome function

Turn rRNA into protein through translation

Organelles within the endomembrane system

Nucleus, ER, Golgi apparatus, lyosomes, vacuoles, and plasma membrane

Vesicle

Small fluid-filled sac with a lipid bilayer membrane that stores, transports, or digests/engulfs substances in a cell

Nucleus

Contains chromosomes, controls mRNA synthesis and export

Nuclear envelope

A double membrane composed of lipid bilayers

Nuclear lamina

Protein filaments that act as scaffolds providing structure

Nucleolus

Location of rRNA

Smooth ER

Metabolic processes include lipid synthesis, drug detox, calcium storage

Rough ER

Covered in ribosomes, assists with protein glycosylation and membrane synthesis

Golgi apparatus

Sorts molecules, releases vesicles, produces and secretes carbohydrates

Lysosomes

Membrane sacs with acidic interior that contain hydrolytic enzymes which hydrolyze macromolecules and facilitates cell turnover

Vacuoles

Large vesicles that store water, nutrients, and waste

Mitochondria

Site of cellular respiration which produces ATP from food and oxygen

Chloroplast

Site of photosynthesis, produce sugar from CO2, water, and light

What is endosymbiotic theory

Theorizes evolution of chloroplast and mitochondria by a eukaryote engulfing a nonphotosynthetic prokaryote which evolved into a mitochondrion and engulfing a photosynthetic prokaryote which evolved into a chloroplast

Evidence for endosymbiotic theory

Mitochondria and chloroplasts have their own DNA, have double membranes, and reproduce independently through binary fission

Cytoskeleton

Dynamic network of fibres extending through cytoplasm consisting of microtubules (tubulin polymers), microfilaments (actin filaments), intermediate filaments (some cells), it provides structure/support and anchors organelles

Microtubules

Resist compression/”stress ball” squishing, related to motility

Microfilaments

Resist tension like a rubber band

Plasma membrane

Lipid bilayer consisting of phospholipids

Phospholipids

Hydrophilic heads and hydrophobic tails, self-assemble into bilayers

Selectively permeable

Regulates what goes in and out, some molecules can go through, others can’t or need help

Integral proteins

A protein embedded in the hydrophobic portion of the membrane (must also be non-polar)

Peripheral protein

Associated with, but not embedded in, the membrane

Saturated lipid components

Carbons connected only by single bonds consisting of straight chains that pack tightly in the bilayer

Unsaturated lipid components

Carbons connected by 1+ double bonds becoming “kinked”, kinked tails prevent packing

Temperature and fluidity

Unsaturated fatty acids create space for membrane fluidity in the cold and prevent rigidity and saturated fatty acids increase rigidity in the heat as needed

Cholesterol function

Acts as a buffer preventing membrane from becoming overly fluid in high temps (fills gaps) or overly rigid in low temps (creates gaps)

Diffusion

Molecules move from high to low concentration until dynamic equilibrium is achieved, overall moving from high to low but always moving back and forth

Electrochemical gradient

Diffusion gradient of an ion determined by ion concentration as well as membrane potential

Why do electrochemical gradients cause motion

A high concentration of positive ions results in a net positive charge and vice versa, therefore molecules will diffuse to create net neutral charges

Tonicity

Solution’s affinity to cause water loss in a cell

Isotonic

Solute concentration is equal to inside the cell

Hypotonic

Solute concentration is lower than inside the cell, water flows in

Hypertonic

Solute concentration is higher than inside the cell, water flows out, plants/animals become shriveled/plasmolyzed

Passive transport

Diffusion across membrane according to electrochemical gradient

Facilitated diffusion

A type of passive transport facilitated by transport proteins

Active transport

Requires ATP hydrolysis in some way, moving against gradient

Symport

Moves in same direction

Antiport

Cotransporter that moves in opposite directions