Biology Flashcards
scientific thinking steps in order
- observe
- hypothesize
- predict
- experiment
- conclusion
what is an element
- 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
basic atomic structure
- nucleus is composed of protons & neutrons
- the nucleus is surrounded by a cloud of electrons
what are isotopes?
- atoms that have the same # of protons, but more or fewer neutrons
what determines an atoms properties?
of protons
how many elements are in the human body & what are the BIG FOUR?
- 25 elements
- oxygen, carbon, hydrogen, nitrogen
what determine’s how an atom will bond?
- electrons
the number of protons in an atom is equal to:
- the number of electrons
why is carbon so important for life?
- carbon is able to share its 4 valence electrons with up to 4 other atoms
- a huge variety of complex molecules are possible
- carbon mostly bonds w/ oxygen, nitrogen, hydrogen & other carbons
what are ions?
- charged atoms
ionic bonds:
- TRADE of electrons
- two oppositely charged ions attract each other
- results in neutral compound
- ex: NaCl
covalent bonds:
- two atoms SHARE electrons
- electron cloud surrounds both atoms
- single or double covalent bonds
- STRONGEST bond
- ex: skin
hydrogen bonds:
- bonds between a slightly positive hydrogen atom in one molecule and a slightly negative atom in the other molecule
- weakest chemical bond
- ex: water-water
why is water crucial to life:
- hydrogen bonds = water cohesive for carrying nutrients
- high heat capacity (heat absorption form sun)
- lower density when frozen (ice floats)
- universal solvent
what is acidity?
- the amount of hydrogen in a solution
- pH (potential of Hydrogen)
acids:
- pH lower than 7.0
- higher concentration of H+
- H+ is very reactive
- ex in order from most acidic: stomach acid, soda, orange juice, coffee
bases:
- pH higher than 7.0
- higher concentration of OH-
- ex in order from least basic: blood, baking soda, ammonia, bleach
blood pH contains:
- buffers
- can quickly absorb excess H+ ions to keep a solution from being too acidic
- and quickly release H+ ions to counteract any increases in OH- concentration
the four major macromolecules:
- carbohydrates
- lipids
- proteins
- nucleic acids
carbohydrates:
- carbon + H2O
- primary fuel for cells
- form structure of cells in all organisms
- composed of monosaccharides = simple sugar
lipids:
- significantly more C-H bonds than carbs
- more storable energy
- triglycerides = 3 carbons with fatty acid tails
- fatty acid tails = carbon with hydrogen attached (acid bc of Oxygen)
saturated fats:
- each carbon in hydrocarbon chain is bound to two H atoms = tends to be solid @ room temp.
- bonds form a linear structure
- ex: cheese
unsaturated fats:
- at least 1 double bond link 2 carbon atoms in the hydrocarbon chain
- liquid at room temp
- bonds form a crooked shape
- ex: olive oil
what is hydrogenation?
- chemical process / artificial addition of hydrogen atoms to an unsaturated fat to make the fat more saturated
- straightens the hydrocarbon tail shape by converting some of the double bonds to single
- our bodies don’t digest these well
cholesterol:
- semi rigid ring structure, a sterol
- all sterols have 4 fused carbon rings
- important component of cell membrane
steroid hormones:
- based on cholesterol
- estrogen & testosterone
- estrogen = regulation of memory & mood
- testosterone = muscle growth
phospholipids:
- major component of cell membrane
- negative charge
- hydrophilic
- two fatty acid chains & phosphorus atom in the glycerol “head” region
- double layer in every cell of our body = phospholipid bilayer
proteins:
- composed of C,H,O & nitrogen
- structural, protection, regulation, enzymatic, transport, DNA making
- made up of amino acids
- 9 essential amino acids
enzymes:
- proteins that increase likelihood for a reaction to occur
- speed up chemical reactions in the body
- lower activation energy needed for processes
mutations
- incorrect amino acid sequences
- nonfunctional enzymes
- essential to evolution
nucleic acids:
- of the nucleus
- make of nucleotides = molecule of sugar, phosphate group, & nitrogenous base
- carry genetic info (ATGC)
DNA:
- deoxyribonucleic acid
- ATGC
- hydrogen bonds hold AT / GC together
- double stranded
RNA:
- ribonucleic acid
- single stranded
- AU / GC
cell
smallest unit of life that can function independently & perform the necessary functions of life & reproduce
cell theory
- all living organisms are made up of cells
- cells come from preexisting cells
eukaryotic cells
- contains a nucleus (DNA)
- contain specialized subregions (organelles)
prokaryotic cells
- don’t have a nucleus
- DNA resides in middle of the cell
- 2/3 of all living organisms
prokaryotic cell structure:
- plasma membrane = encloses contents
- cytoplasm = fluid inside the cell
- DNA = genetic info
- ribosomes = genetic info into protein structure
- cell wall = protect & shape cell
- capsule = protective outer coating
- pili = hair-like projections for attachment
- flagellum = whip-like projection(s) for cellular movement
rough endoplasmic reticulum
- picks up RNA and turns them into proteins
- transports proteins to the smooth ER
- rough = covered in ribosomes
smooth endoplasmic reticulum
- synthesizes sterols & lipids
- sends these to the Golgi
- liver cells contain much smooth ER for detoxifying
golgi apparatus
- tells proteins where to go
mitochondria
- ATP maker
- different cells have different # of mitochondria depending on energy needs
- ex: liver cells have >2,500 mito, RBC have 0 mito. (mitos. eat oxygen)
lysosome
- breaks down everything
- breaks down proteins & RNA & viruses
- digestive enzymes
- acidic
organelles that specifically plant cells have
- chloroplasts = convert energy obtained from sun
- vacuole (found in some animal cells) = water storage & waste disposal
- cell wall = helps the plant have a rigid stalk
endosymbiosis theory
- explains the presence of chloroplasts & mitochondria
- mito & chloro = also contain DNA
- both divide by splitting (fission)
- DNA in mito & chloro are more related to bacterial DNA
purpose of the plasma membrane
- synthesize & store energy
- hold contents of cell in place
- take in nutrients
- allows interaction w/ environment & other cells
- phospholipid bilayer
recognition proteins
- markers that ID cells
membrane proteins
- structure
- accelerate reactions on the plasma membrane
transport proteins
- provide passageway for molecules through cell
receptor proteins
- bind to external chemicals that regulate processes within the cell
- send / receive signals
simple diffusion
- molecules pass directly through plasma membrane without assistance of another molecule
facilitated diffusion
- molecules move across plasma membrane with help of a channel or carrier molecule
osmosis
- passive diffusion of water across a membrane