Biology Exam 1 Study Flashcards
What are the steps of scientific thinking?
Observe, hypothesize, predict, experiment, & conclusion
What is a null hypothesis?
a negative statement proposing that no relationship exists between two factors
What does a good hypothesis do?
generate a testable prediction
What are theories?
-hypotheses of which scientists are most certain of
-have been repeatedly tested
-are broader in scope than hypotheses
What is a blind experiment design?
the experimental subject don’t know which treatment (if any) they are recieving
What is a double-blind experiment?
neither subject nor experimenter knows which treatment (if any) the subjects are receiving
Technology is not science, it is:
the application of research
What are some characteristics of all living organisms?
-complex, ordered, consisting of one or more cells
-uses and transforms energy to perform work
-responds to external environment
-regulation & homeostasis, growth, evolution
What is an element?
a pure substance that cannot be broken down chemically into other substances
What is an atom?
a bit of matter that cannot be subdivided any further without losing its essential properties
What is an isotope?
an atom of the same element that has a different number of neutrons
How many elements make up the human body? What are the big 4?
-25
-Oxygen, Nitrogen, Carbon, Hydrogen
An atom’s electrons determine:
whether (and how) the atom will bond together
of protons is equal to
of electrons
What’s so special about carbon?
-it is able to share its 4 valence electrons with up to 4 other atoms
-this means a huge variety of complex molecules are possible
-carbon mostly bonds with the big 4
What are ions?
charged atoms
Describe ionic bonds
-a TRADE of electrons
-two oppositely charged ions attract each other
-results in neutral compounds
-strong bond
-ex:salt
Describe covalent bonds
-2 atoms SHARE electrons
-the electron cloud surrounds them both
-single or double covalent bond
-strongest bond
-ex: skin, a desk, the floor
Describe hydrogen bonds
-bonds between a slightly positive hydrogen atom and a slightly negative atom in another molecule
-weakest bond
-ex: water
What are molecules?
a group of atoms chemically bonded
Bond energy is dependent on ?
the atoms involved
Chemical reactions:
involve the breaking and forming of bonds
Why is water crucial to life?
-hydrogen bonds make water cohesive (water carries nutrients)
-high heat capacity (water absorbs heat from the sun)
-lower density when frozen (ice floats, life can still live under ice)
-it’s a good solvent (good for breaking up molecules = easier to carry out chemical reactions)
What is pH?
-potential of hydrogen
-the amount of H+ molecules in a solution
-measure of acidity
Acids:
-pH lower than 7.0
-higher concentration of h+
-can donate H+ to other chemicals
List some acids (least to most acidic)
-coffee
-orange juice
-soda
-stomach acid
Bases:
-pH higher than 7.0
-higher concentration of OH-
-neutralize acids by bringing H+ and OH-
List some bases (weakest to strongest)
-blood
-baking soda
-ammonia
-bleach
What are macromolecules?
large organic molecules made up of smaller subunits
what does organic mean ?
“of life”
What are the 4 major macromolecules?
-carbohydrates
-lipids
-proteins
-nucleic acids
Describe carbohydrates
-carbon + h2o “hydrate”
-energy
-C-H bonds store large amounts of energy
-primary fuel for cells
-form the structure of cells in all organisms
-composed of monosaccharides
What are monosaccharides ?
simple sugars (contain 3-6 carbon atoms)
What do carbohydrates do for your blood sugar?
-fuel for cellular activity
-glycogen for short term storage
-fat for long term storage
What are disaccharides ?
-lactose
-sucrose (table sugar)
-formed by the union of two simple sugars
What are polysaccharides ?
-starch
-formed by the union of many simple sugars
-this = complex carbohydrates
What are complex carbohydrates ?
-chitin: animals/insects have hard shells that cannot be digested
-cellulose: plants/tress can be used to build & as dietary fiber which helps clear the digestive track
What are the common monosaccharides (also give their chemical formula)
-glucose (C6H12O6)
-fructose (C6H12O6)
-galactose (C6H12O6)
Describe lipids
-contain significantly more C-H bonds = more stored energy
-made up of glycerol and fatty acids
-high density energy
-insoluble in water = nonpolar molecules
What does hydrophobic mean?
doesn’t like water
What does hydrophilic mean?
loves water
Describe the process of triglycerides
-glycerol is a hydrophilic sugar, made up of 3 carbons
-these carbons have fatty acid (hydrophobic) tails
-the fatty acid tails are carbon chains with hydrogens attached
-they are acids because of the oxygen attached to it
Describe saturated fats
-each carbon in the hydrocarbon chain is bound to two H atoms
-tend to be solid at room tem
-cheese
-molecules line up
Describe unsaturated fats
-at least one double bond link two carbon atoms in the hydrocarbon chain
-liquid at room temp
-olive oil
-molecules have a crooked shape
What is hydrogenation?
a chemical process that involves artificially adding hydrogen atoms to an unsaturated fat in order to make it more saturated
What does hydrogenation do to the chemical bonds?
-makes the hydrocarbon tail straighter
-converts some of the double bonds in the tail to single bonds
-our body doesn’t digest these well
What is cholesterol?
-a lipid with semi rigid ring structure (hexagon)
-forms sterols
-important component of cell membranes in animals
-90% of the cholesterol in your body, your own body makes
What are steroid hormones?
-based on cholesterol
-made of four carbon fused rings
-estrogen = regulation of memory and mood
-testosterone = muscle growth
What are phospholipids?
-major component of the cell membrane
-negative charge
-hydrophilic
-two fatty acid chains and a phosphorous atom in the glycerol “head” region
-every cell in our body has a double layer of phospholipids
Describe proteins
-bodybuilding macromolecules
-made up of C H O and N (big 4)
-they help with structure, protection, regulation, making DNA
-enzymatic
made up of amino acids
Describe amino acids
-amino(positive charge) bonded with carboxyl(negative charge) bonded with a side chain (this side chain is what differentiates the different amino acids
-20 different amino acids
-7 essential amino acids we need to get from our diet
Describe the primary structure of proteins
linear order
Describe the secondary structure of proteins
2d beta plated sheet
Describe the tertiary structure of proteins
interaction of the secondary structures
Describe the quaternary structure of proteins
multiple subunits
What factors can denature a protein?
-extreme environments
-temperature changes
-pH changes
What are enzymes?
-proteins that increase the likelihood of a reaction occurring
What do enzymes do?
-they break things apart or put things together
-this is the most important thing that proteins do
-speed up chemical reactions
-make reactions possible at our body temperature
What is activation energy?
-the push that is needed for chemical reactions to occur
-enzymes can act as a catalyst by lowering the activation energy
What are mutations?
-incorrect amino acid sequence
-nonfunctional enzymes
Describe nucleic acids
-“of the nucleus”
-nucleotide is the building block
-carry genetic info (ATGC)
What do nucleotides consist of?
-a molecule of sugar
-phosphate group
-nitrogenous base
What is DNA?
deoxyribonucleic acid (ATCG)
What is RNA?
-ribonucleic acid (AUGC)
-RNA direct the production of proteins
-acts as a middleman molecule (DNA > RNA > protein)
What bonds A-T or C-G?
hydrogen bonds
DNA & RNA differences:
-sugar molecule of the sugar phosphate backbone: ribose in RNA / deoxyribose in DNA
-RNA is single stranded
-Uracil (U) replaces thymine (T)
How do enzymes regulate reactions?
-they can saturate the system (you can’t make more)
-high temperatures can increase reaction rates (only to certain extent bc eventually the proteins will become denatured
-reaction rate generally increases as pH nears optimum level for an enzyme
What do inhibitors do?
prevent reactions by blocking enzymes
What do activators do?
increase reactions
What provides energy to the body?
glucose
