Bio Test 1: The Origin of Life

Biology

the study of life

Big Bang

13.8 billion yrs ago, an explosion occurred and all matter came to be

stellar fusion

gravity forms stars

supernovas and cosmic collisions

create heavier elements

6 Major components to life

1. all living things maintain high organization

2. acquire/use materials and energy

3. sense and respond to stimuli

4. growth/development

5. reproduce

6. evolve

1. all living things maintain high organization

all living things are made of cells

plasma membranes

keep bad things out and good things in

compartmentalization

all cells have boundaries

structure vs. function

structure: shape of something

function: what it does

2. acquire/use materials and energy

metabolism: sum of all chemical activity taking place in an organism (break down nutrients)

regulation

internal constancy

equilibrium

equal amounts on sides of barrier (equal in/equal out)

homeostasis

constant internal environment, essential to life, non-stop chemical replacement

autopoiesis

organisms self make the components necessary to maintain itself

3. respond to stimuli

all organisms perceive and exhibit behavior in response to stimuli

Behavior can be

instinctive: present in a living thing from birth’

learned: resulting from experience ex: photo trophism: growing towards the sun

4. growth and development

development: when a growing organism becomes more complex

5. reproduce

asexually: dividing in half (1 parent)

sexually: producing seeds (2 parents)

DNA and genes

DNA: chemical material of genes

Genes: units of inheritance that transmit info from parent to offspring, bases include Adenine, Thymine, Cytosine, Guanine

6. evolution

all organisms are related by common ancestry and have changed over time, Charles Darwin and Alfred Russel Wallace

homeobox genes

specific to body planning

natural selection

individuals possess traits that help them survive and reproduce and can result in adaptations

adaptations

changes in structure, physiology, or behaviors that aid in survival and reproductive success

Last Universal Common Ancestor (LUCA)

first organism

Taxonomy

classifying organisms into smaller groups of relatedness

phylogeny

study of evolutionary relationships with genetic similarities as primary way of sorting

bacteria and archaea

prokaryotic (simple, smaller, no nucleus)

eukarya

eukaryotic (complex, larger, multicellular life, nucleus)

scientific theory

accepted as facts, start as hypothesis but growing evidence

scientific law

mathematically predictable, NOT evolution

life

life formed before free-oxygen was available, earth, prokaryotic, eukaryotic, multicellular

earth

took 1.5 billion years for life to start metabolizing and reproducing after it formed

many compounds in abundance but no free oxygen

earth’s sources of energy

lightning, volcanic activity, radiation

momentum in life

organic molecules synthesized into macromolecules that interacted, processes became more complex

outdated idea

believed new species sprang into being spontaneously from nonliving matter

Francesco Redi (1668)

disproved maggots spontaneously form on meat

Pasteur and Tyndall (1800s)

disproved microorganisms grow in sterile broth

primordial soup theory (Oparin and Haldone)

life began from organic molecules formed near Earth’s surface/pond/ocean

Oparin and Haldone

independently proposed that organic molecules could form basic materials on earth, some compounds accumulated more which made a supply of preobiotics

prebiotics

organic compounds essential to life, big step in evolution of matter towards life

Miller-Urrey Experiment

tested soup theory by mixing gases and shocking them with electric shocks. Produced amino acids, sugars, lipids, nucleic acid parts, showing theory is possible. Did NOT produce nucleotides

issues wirh soup theory

dilute, exposed

Iron-Sulfer World Hypothesis (Primordial Pizza)

Gunter Wachterhauser. prebiotics were developed on clay surfaces near hydrothermal vents of the seafloor. Larger, complex compounds formed (RNA)

Iron-Sulfer World Hypothesis (Primordial Pizza)

thermal energy, Iron and Sulfer move electrons around catalyzing reactions, beginning of autotrophic metabolism and RNA

Ridge smokers

silts form compartments and biological molecules accumulate in cell sized enclosures, prebiotics are found here

RNA

energetically easier to make, breaks down faster than DNA, can catalyze chemical reactions, likely first self-replicating molecule, almost identical to DNA structurally.

DNA

replication requires large complex enzymes, requires lots of energy, instructions for building enzymes are coded in DNA

Ribozymes (Thomas Cech and Sidney Altman)

RNA molecule that catalyzes metabolic reactions, cut and make RNAs, splice RNA fragments together, attaches amino acids to proteins

vesicle

simple hollow spheres composed of lipids and proteins, precursors to cells, formed by agitating water that contains lipids and proteins

protocell

structurally similar to a cell but not alive, vesicle with more complex insides

autotroph

synthesizes their own molecules using an external energy source (sunlight)

heterotroph

obtain the molecules needed from environment (humans)

anaerobic

dont use oxygen in their metabolic process

aerobic

uses oxygen in their metabolic process

matter

anything that occupies space and mass, life is composed of matter

chemical composition of body

25 elements are essential to people, main ones are Hydrogen, Carbon, Oxygen, Nitrogen

trace elements

required in only very small amounts

atom

smallest unit of matter

element

consists of a single kind of atom (92)

nucleus

contains protons and neutrons

electrons

negative, attracted to protons, the more electrons the more shells

atomic number

number of protons

atomic mass

how much matter it contains, protons + neutrons

isotopes

element with 2 or more atomic forms (# of nuetrons vary)

radioisotopes

break down and emit radiation

molecules

2 or more atoms linked together

compound

type of molecule with 2 or more elements combined in a fixed ratio (NaCl, glucose, water)

ionic bonds

transfer electrons, formed between oppositely charged ions, weak (NaCl)

ions

atoms that have lost or gained electrons and become electrically charged

covalent bond

two atoms share pairs of electrons, strongest, hold atoms together in a molecule (water)

polar molecule

one with an uneven distribution of charge

hydrogen bond

polarity of water molecules, results in weak electrical attractions to other water molecules, BETWEEN water molecules

cohesion

water molecules stick together as a result of hydrogen bonding, between molecules NOT within molecules

water moderates temp

water resists temp change, Earth’s water supply enables temps on planet to stay within limits that permit life by storing heat from sun and releasing it during cooler periods

regulates internal temp

water helps regulate constant temp inside cells

evaporative cooling

a substance evaporates and the surface of the liquid remaining cools down (sweat, panting)

ice floating

ice floats because it is less dense than water because the space between the molecules expands forming ice. acts as an insulating blanket over water allowing life to persist under the ice

solvent

substance that dissolves another compound

solute

compound that gets dissolved

aqueous solution

water and dissolved solute

acid

chemical compound that releases hydrogen to a solution (stomach acid)

base

a compound that accepts hydrogen and removes them from solution (bleach)

ph scale

measure of the Hydrogen ion concentration in a solution, 0(acidic)-14(basic)

physiological ph

7.4, ph affects chemical reactions

instability in ph

instability for metabolism, DNA synthesis, synaptic firing, heart beating, exhaling CO2

Alkalosis

increase in physiologic ph

causes: excessive sweating or vomiting, poor oxygenation

acidosis

decrease in physiologic ph

causes: lung and kidney disease

hydrophilic substances

interact with water readily, polar molecules

hydrophobic substances

dont interact readily with water, non-polar molecules, important in membrane formation in cells (oil)