[Bio HL1, Fall Semester Final]

Polarity

The property of molecules having a partial positive charge on one atom and a partial negative charge on another atom.

Hydrogen bonds

The weak bonds formed between the positive hydrogen atom of one water molecule and the negative oxygen atom of another water molecule

Cohesion

The ability of water molecules to stick together, allowing them to form a continuous stream

Surface tension

The property of water that allows small organisms to move along its surface and live around it as a habitat

Adhesion

The ability of water molecules to stick to other polar molecules, allowing water to flow through narrow paths and against gravity

Capillary action

Movement that results when water flows through a narrow path without help from gravity.

Solvent properties

The ability of water to dissolve substances that are charged or polar, creating solutions

Hydration shell

The sphere of water molecules around a dissolved ion using opposite charges

Amphipathic

Having both a hydrophilic region and a hydrophobic region

Metabolism

The sum of all chemical reactions that occur in an organism, facilitated by water as a medium

Buoyancy

The property of water that describes the upward force exerted by a fluid on an object immersed in it, allows organisms to float in water

Viscosity

The stickiness of a fluid, influenced by the internal friction created when the fluid moves

Thermal conductivity

The property of water which describes the rate at which heat passes through a substance, with water being higher than that of air

High specific heat

The property of water that requires a large amount of energy to raise its temperature, resulting in a stable environment

Origin of Water

The theory that water on Earth was delivered by colliding asteroids during the early years of the planet

Retention of Water

The ability of Earth to retain water due to its distance from the Sun and its strong gravity

Goldilocks Zone

The region around a star where conditions are just right for the presence of liquid water and the potential for extraterrestrial life

Goldilocks Zone

The region around a star where conditions are just right for the presence of liquid water and the potential for extraterrestrial life

Pre-biotic Earth

[O2] was low therefore no ozone; [CH4] and [CO2] was high; temp was high due to greenhouse gases; there was much lighting

Abiogenesis

Spontaneous origin of cells from non-living sources

Catalysis, self-assembly, compartmentalization, self-replication

Four requirements that must have happened for abiogenesis to occur

Miller-Urey's Experiment

Demonstrated abiogenesis; boiled vapors; added H2, CH4, NH3, removed O2; added electrical discharge; produced 20AAs

Significance of Vesicles

Separated "self" from environment; created unique internal chemistry

Significance of RNA

Self-replicating; can work as an enzyme

Ribozymes

RNA molecules that work as catalysts

LUCA

Last Universal Common Ancestor; microbe that existed ~4 to ~4.5 BYA

Estimation of Dates

Using isotope ratios and genomic analysis

Cell Theory (Robert Hooke)

Cells are the smallest unit of life;
all living organisms are composed of cells;
cells come from pre-existing cells

Structures No Longer Considered Organelles

Cell wall, Cytoskeleton, Cytoplasm

Universal Structures (3)

Plasma Membrane, Cy DNA, Ribosomes

Plasma Membrane (Universal Structure)

Structure: phospholipid bilayer with embedded proteins and cholesterol

Function: Semi-permeable barrier that separates internal/external environment; controls entry/exit of substance

DNA (Universal Structure)

Structure: double helix made of nucleotides

Function: contains instructions for all cell functions, specifically making proteins

Ribosomes (Universal Structure)

Structure:
2 subunits (large and small) made of rRNA and proteins
no membrane
two different sizes

Function: Protein synthesis

70S vs. 80S

Prokaryotes have 70S, Eukaryotes have 80S (larger)

Svedberg units (Ribosomes)

Measurement of the relative size of cell parts through sedimentation during centrifugation

Free vs Bound Ribosomes

Free ribosomes make proteins to be used in cytosol (In Cell)

Bound ribosomes make secretory proteins, like hormones

*ribosomes structurally identical and interchangeable*

**every ribosome initially free, then when needs to make secretory protein, becomes bound to ER**

Prokaryote Structure

nucleoid, naked DNA, 70S ribosomes, cytoplasm, plasma membrane, cell wall (thicker), pili/cilia, flagella
*shape is more rod-shaped, length 2x width*

Nucleoid (Prokaryotes only)

Area where circular DNA is found

Genophore (Prokaryotes only)

Single, main DNA of prokaryotes

Plasmids (Prokaryotes only)

Extra circular DNA w/ additional info

Prokaryote Ribosome Size

70S

Mesosomes (Prokaryotes only)

Infoldings that increase surface area and act as sites for cellular respiration

Cell Wall (Prokaryote)

Made of peptidoglycan, protects cell, maintains shape, prevents bursting (prokaryote cell wants to be a bit turgid)

Flagella

Long, slender extensions used for movement

Cilia (Sex pili)

Hair-like, sticks to surfaces, used in bacterial conjugation

Nucleus

Structure: nuclear envelope is double membraned (2 phospholipid bilayers) with pores; contains nucleolus

Function: stores genetic info as chromatin (DNA + Histones)

Nucleolus (Both)

Region in nucleus for ribosome synthesis (proteins for ribosomes synthesized outside of nucleus, travel in to join w/ rRNA)

Chromatin

Form in which genetic information is stored in cells (DNA + histone proteins)

Benefits of Double Nuclear Membrane

Hydrophobic core is never exposed to water (if punctured, it seals itself), transportation of materials in & out of nucleus; allows membrane break down and chromosomes to move to opposite poles of the cell

Rough Endoplasmic Reticulum (rER) (Both)

Structure: made of cisternae, has 80S ribosomes attached

Function: folds/packages secretory proteins (typically hormones)

Cisternae

Flattened membrane sacs (folds)

Smooth Endoplasmic Reticulum (sER) (Both)

Structure: made of branched, tubular membranes;
NO RIBOSOMES

Function: makes lipids (phospholipids/hormones), detoxifies drugs, stores calcium ions for muscles

Golgi Apparatus (Both)

Structure: consists of cisternae

Function: receives vesicles from the rER (cis face); modifies and ships most to plasma membrane for secretion (trans face)

*cis face always faces the nucleus*

Vesicle Transport Model

Cisternae remains static, vesicles move proteins between them

Cisternal Maturation Model

Vesicles from rER coalesce to from new cisternae on cis side which matures and moves to trans side, which then breaks into vesicles

Lysosomes (Only animal cells)

Structure: membrane sacs filled with hydrolytic enzymes from Golgi

Function: digests food, organelles, and sometimes entire cell (apoptosis)

Mitochondria (Both)

Structure: Double membrane, like nucleus (outer membrane is smoother, inner contains cristae); matrix (fluid) inside; has own DNA and ribosomes, makes own proteins

Function: cellular respiration, makes ATP

Cristae

Infoldings of the inner membrane of a mitochondrion that houses the electon transport chain for synthesis of ATP.

Matrix

Center compartment of the mitochondrion that contains dissolved enzymes in fluid

Sap Vacuoles (Both)

Structure: single membraned sack filled with fluid, contains dissolved materials

Function: store food (animal cells), store poison, pigments (plant cells), expel water (contractile vacuole in paramecium)

Central Vacuole (Only plant cells)

Found only in plant cells, stores water, pigments, poison, and maintains hydrostatic pressure

Vacuole vs. Vesicle

Large vs. small;
permanent vs. temporary

Adaptations of Vesicles

Moves contents within;
moves membrane or proteins that makeup vesicles

Clathrin

Three-legged protein that positions itself on the surface of membranes which then forms vesicles

Cytoskeleton (Both)

Microtubules (largest) and microfilaments (smallest)

Microtubules

Structure: made of tubulin protein

Function: found in mitotic spindle fibers; cilia/flagella;
moves organelles within cell (ex. vesicles)

Microfilaments

Structure: made of actin protein

Function: cytoplasmic streaming (when you circulate cytosol to transport food/enzymes); muscle contraction;
helps animal cells maintain shape

Centrosome (Only animal cells)

Structure: contains 2 paired centrioles;
each centriole made of 9 triplet microtubules

Function: used as spindle fibers in mitosis/meiosis

Chloroplast (Only plant cells)

Structure: double membrane;
contains stacks of thylakoids inside (in stacks called granum)

Function: photosynthesis;
makes glucose, stored as starch grains

Cell Wall

Structure: rigid outer layer made of cellulose

Function: provides support, protection, prevents excess water uptake, lets plant cell remain upright

Differences between Animal/Plant/Fungi

plastids, cell wall, vacuole, centrioles, undulipodia

Plastids differences in eukaryotic cells

organelle w/ 2 outer membranes and internal sacs;
not in animal/fungi;
in plant cell in chloroplasts and amyloplasts (starch storage)

Cell Wall differences in eukaryotic cells

not in animal cell;

made of chitin in fungi;

made of cellulose in plant cells

Vacuole differences in eukaryotic cells

animal cell, small/temporary;
in plant/fungi, large/permanent

Centrioles differences in eukaryotic cells

in animal cell, microtubule spindles and cilia/flagella;
not in plant/fungi except in swimming male gametes

Undulipodia differences in eukaryotic cells

cilia/flagella to generate movement;
present in animal cells, including male gametes;
absent in plant/fungi except in swimming male gamete

Cell wall differences (one more time)

prokaryotes - made of peptidoglycan;
fungi - made of chitin;
plant cells - made of cellulose

Atypical Cell Structures

Red blood cell, skeletal muscles, aseptate fungal hyphae

Red Blood Cell

no nucleus;
lets cell be smaller/more flexible/carry more O2;
cannot repair itself (live ~3 months)

Skeletal Muscles

cells fuse together and become large & multinucleate (more than one nucleus);
a muscle fiber (bunch of cells fused together w/ many nuclei); can be as long as 30 cm

Aseptate Fungal Hyphae

nucleus divides first w/o cell division;
produces cell walls;
results in some cells w/out a nucleus and some with multiple
"aseptate" = w/out nucleus

Magnification Formula

Magnification = size of image/size of specimen

1 mm

= 1,000 micrometers
=1,000,000 nanometers

Electron Microscopy

utilizes wavelengths of electrons focused by electromagnets;
has higher magnification (x1 Million) and good resolution (clear image);
kills specimen and only in black/white

Freeze Fracture

-produces images of surfaces within cells
-rapidly freeze sample in liquid propane
-use steel blade to fracture sample
-etch - remove ice crystals via vaporization
-coat - pour vapors of platinum/carbon to form replica (like a mold)

Cryogenic Electron Microscopy (Cryo-EM)

-captures how proteins change form to carry out function
-flash freeze thin layer of protein solution
-place in electron microscope
-take many images, due to random orientation of protein in solution, use algorithms to produce 3D image of proteins

Fluorescent Stains

sample absorbs light & re-emits at longer wavelength, producing color that can be detected

Immunofluorescence

method of tagging antibodies with a fluorescent markers to detect specific proteins (antigens)

Endosymbiosis

Eukaryotic cells evolved from prokaryotes engulfing other prokaryotes via phagocytosis;
developed a symbiotic relationship;
larger provided protection, smaller provided energy

Endosymbiont

a cell that lives within another with mutual benefits

Evidence of Endosymbiosis

Mitochondria & Chloroplasts have:
• own DNA - circular & naked like prokaryotes
• own ribosomes - 70S in size like prokaryotes
• double membrane - outer may initially have been a vesicle
• reproduces through a fission-like process
• affected by antibiotics - suggests bacterial origins

Functions of life in unicellular organisms (8)

Nutrition, metabolism, growth, response to stimuli, excretion, homeostasis, movement, reproduction

Nutrition

Supply of food & gasses from environment for energy, growth and repair

Metabolism

Sum of all biochemical rxns in organism (ex. cellular respiration)

Growth

Increase in size or number of cells over time

Response to Stimuli

Perception of internal/external stimuli and responding appropriately

Excretion

Removal of waste (CO2, urea, feces)

Homeostasis

Maintenance stable, internal conditions

Movement

Change in physical location or position from rest to motion & vice versa

Reproduction

Production of offspring and passing on genes