Biology-exam one

What is biology and why study of life at multiple levels

-Biology is the scientific study of life

-studying life helps us understand the world around us and study how things interact

Hypothesis v. scientific theory

-Hypothesis: prediction based off information provided

-Scientific theory: extensive tests done backed by evidence

Observation→ Hypothesis

Observation → question → hypothesis → prediction → experiment/observation → data → conclusion

Test group and control group. Importance of both

-Test group receives the experiment treatment.

-Control group does not and is used for comparison

-both are needed to determine whether the independent variable caused the observed change

How did scientists infer the asteroids impact cause dinosaur extinction

-iridium in rock layers at extinction time; shocked quartz crystals from impact; crater of the right size and age in Yucatan, Mexico

What characteristics distinguish living organisms

-Reproduction

-respond to their environment

-have capacity to evolve

-acquire, transform, and use energy

-are organized

What are the three key features of cells

-ability to separate and regulate internal environment

-ability to store and transfer information

-ability to acquire transform and use energy

What does it mean to say that a cell is lifes functional unit

-basic unit of life

-all living things made up from cells

-things come from preexisting cells

How does natural selection work

-variation exists- some variation is heritable; environment creates differences in survival/reproduction; some traits associated with greater reproduction success becomes more common over generations

What do phylogenetic trees show

-evolution and evolving

-three domains: bacteria, archaea, eukarya

How are ecology and evolution connected

-Ecology: how organisms interact

-Evolution: organisms evolving

-ecology can explain evolution

Polydenylation

required for export of transcript to cytoplasm

Why might mice living in sand dunes have light tan fur

natural selection

-mice with tan fur survive longer

What are the parts of an atom and where are they located

-proton, nucleus, neutron, electron

-protons & neutrons in nucleus; electrons in electron orbitals/shells around the nucleus

atomic number v. atomic mass

-protons: atomic number

-protons + neutrons= atomic mass

why are valence electrons important

-are in the outermost shells

-determine how many bonds an atom can make

Covalent v. ionic bonds

covalent: atoms share electrons

ionic: one atom transfers electrons to another, creating oppositely charged ions that attract

polar v non polar covalent bonds

polar: electrons shared unequally

non-polar: electrons shared equally

-water is polar

How do hydrogen bonds form and why are they important

-positively charged hydrogen, negatively charged oxygen- helps with cohesion

-explains water unusual properties (high boiling points, ice floats, solvent abilities, and cohesion)

Why is water a polar molecule, and what is the difference between hydrophobic and hydrophilic

-polar because O attracts electrons more strongly than H, creating partial charges (isn’t sharing equally)

-hydrophobic: afraid of water

-hydrophilic: loves water

peptide bonds

-hold a chain of amino acids; that creates protein

nucleic acid macromolecules building blocks

nucleotides

protein macromolecule building block

amino acids

carbohydrate macromolecule building block

monosaccharides

lipids macromolecule building block

glycerol + fatty acids (not true polymers)

protein macromolecule job

carry out tasks, form structures

nucleic acid macromolecule job

store/pass genetic info

carbohydrates macromolecule job

energy + structure

lipids macromolecule job

energy storage, membranes, steroid

-hydrophobic

triacylglycerol

3 fatty acids provide energy

steroids

composed of bonded carbons to 4 rings

-cholesterol

phospholipids

fatty acid replaced with phosphorous gene

-major component of plasm membranes

-major lipid in cell membranes

membranes

physically separate cells from external environment

-lipid bilayer

plasma membranes

separate the internal cell from surrounding environment

red blood cells

change shape during osmosis

DNA repetition

preserving sequence of DNA, so copying info can be passed on

What features of carbon allow it to form diverse structures

-carbon can form four covalent bonds

-can form single or double bonds

ester bonds

connects to other lipids

What are the three main ideas of cell theory

-all organisms are made up of cells

-the cell is the fundamental unit of life

-cells come from preexisting cells

what is the purpose of the plasma membrane

-maintains homeostasis

-selective permeability: chooses no matter the size

-semi: size does matter to be considered to be let in or so

Why is the membrane called “fluid mosaic”

-a lot of fluid proteins built in, phospholipid bilayer

-flexible not rigid

How do saturated/unsaturated fatty acids affect membrane fluidity

-saturated: cells are straight not fluid

-unsaturated: bent, very fluid

-cholesterol also affects fluidity

Intergral proteins

internally in the membranes, can’t be removed

peripheral proteins

only on one side of the protein

transmembrane proteins

in the cell, goes all the way through

Diffusion

directly through bilayer

both diffusions

passive: high-low concentration, no energy

facilitated diffusion

needs transport protein (channel or carrier)

What is osmosis

-passive

-movement of water across a membrane

-low to high concentration for solutes

Isotonic

equal solute, cell stable

Hypertonic

more solute outside, water leaves, cell shrinks

Hypotonic

less solute outside, water enters, cell swells/burst

Why do plant cells respond differently to osmosis

-plant cells have a cell wall that is rigid and resists expansion- osmosis stops when water diffuses

-reaches certain point of water, swells to the max it can’t contain more

passive v. active transport

passive: high → low, no energy

active: low → high (against gradient); requires ATP. Primary v. secondary

channel proteins

form a pore that allows specific molecules to pass through without using energy

carrier proteins

bind to a specific molecule and change shape to transport it across the membrane

Prokaryotic cells

-no nucleus

-no membrane bound organelles

-DNA in nucleoid

Both prokaryotic and eukaryotic cells

have DNA

cell membrane

cytoplasm

ribosomes

Eukaryotic cells

-have nucleus

-membrane bound organelles

-larger

What is the endomembrane system

-systems going on in the membrane

-nuclear envelope, ER, Golgi, lysosomes, plasma membrane, vesicles. Modifies, packages, transports lipids and proteins

Rough ER

has ribosomes, synthesizes, proteins

Smooth ER

no ribosomes, synthesizes lipids

What does the Golgi Apparatus do

-receives proteins/lipids from ER, modifies, sorts, packages them, sends to destination/Glycosylation (adds sugars)

-amazon

What are lysosomes

-Vesicles from Golgi with digestive enzymes

-digest enzymes/macromolecules. Maintains pH-5

What is protein sorting into the ER

-sorts by type and function

-ER→ Golgi apparatus → vesicle: then wherever it needs to go

endocytosis

in the cell

exocytosis

out the cell

What is the genetic material and how was it discovered

-DNA

-Griffith: transformation occurred

-Avery/Macleod/McCarty: only Dnase stopped transformation

-DNA is genetic material

nucleotide

nucleoside and 1 or more phosphate group

Nucleoside

sugar and base

Purines

Adenine, Guanine

-base pair= one purine + one pyrimidine

Pyrimidines

-Cytosine

-Thymine

What are phosphodiester bonds

-Connect 3’ carbon of one nucleotide to 5’ carbon of next nucleotide

-create sugar-phosphate backbone. DNA has 5’ and 3’ ends

What does antiparallel and complementary mean

-Antiparallel: strands run opposite directions (5’ →3’ and 3’→5’)

-Complementary: A-T (2 H-bonds), G-C (3 H-bonds)

What stabilizes DNA

-Hydrogen bonds between bases + base stacking interactions

What is the central dogma

-DNA→ RNA → Proteins

-Need DNA to get RNA

-Transcription (DNA → RNA)

-Translation (RNA → protein)

How are DNA and RNA different

-RNA: shorter, ribose, single stranded, has DNA and protein properties

-RNA has ‘U’ instead of ‘T’

-DNA is stable

What is transcription

-DNA strand template for complementary RNA molecule

-Initiation, elongation, termination

-Begins at promoter (TATA box), ends at terminator.

-RNA polymerase builds RNA 5’→ 3’. Template strand is read 3’ → 5’

How is transcription regulated

-Housekeeping genes

-signals some on and off others

Eukaryotic transcription

-transcription in nucleus

-translation in cytoplasm

-RNA processing (5’ cap, poly-A tail, splicing). still has to be modified

Prokaryotic transcription

-primary transcript= mRNA

-no processing

-transcription and translation coupled

-Ends at primary transcript

What are the steps of mRNA processing in eukaryotes

-capping and tailing of splicing

-introns- bases that don’t code

-5’ cap added (7-methylguanosine); poly-A tail added (-250 A’s); splicing removed introns and joins exons

RNA splicing

contains both coding exons and noncoding introns

-splicing catalyses RNA splicing

What is alternative splicing

-introns that don’t code

-one gene can produce different proteins by splicing exons differently