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
tonicity
- balance of a solute in a solution
isotonic solution
- equal balance of solute in solvent
hypotonic solution
- concentration on the outside of the cell is lower than inside
- water diffuses INTO cells
- unlike plant cells, animal cells may explode in hypotonic solutions (lyse)
hypertonic solution
- concentration of solutes outside cell is higher than inside
- cell shrivels up (crenate)
active transport
- movement of molecules into & out of a cell that requires the INPUT OF ENERGY
- primary active transport = uses ATP directly
- secondary active transport = not direct use of ATP
exocytosis
- shuttles molecules out of the cell
- vesicles 1st enclose the particle & then merge with the plasma membrane to release their contents
- dumps large quantities of material outside of cells
- sometimes used by lysosomes
nucleus
- large & most prominent organelle
- genetic control center
- stored DNA info
- composed of nuclear membranes (2 bilayers) w/ pores for protection
- composed of chromatin (aka chromosomes) = fibers of DNA coated with proteins
tight functions
- protein interactions that act like a super glue to tightly attach membranes
- water proof
desmosomes
- proteins that are like velcro
- contain hooks that attach tightly, but allows for signals to transport through
- can be broken apart to release tension
gap junctions
- pores that allow passage of materials between cells
key energy conversion processes:
- photosynthesis
- cellular respiration
kinetic energy
- motion
potential energy
- energy stored in an object
thermodynamic
- heat structure
- 1st law: energy cannot be created or destroyed, only converted
- 2nd law: energy conversion is not perfectly efficient, energy is always lost (in form of heat)
ATP
- adenosine triphosphate
- adenine + ribose sugar + 3 phosphate
- 3 negative charges will repel, so they need a lot of energy to be pushed together
- ATP is used for ALL chemical reactions in the body
- mitochondria produces ATP
- phosphorus is a strong element, hungry for oxygen
photosynthesis:
- uses energy from sunlight to make food (glucose)
- organic molecules are produced
- O2 is a biproduct
- sunlight + water + CO2 –> oxygen & sugar
where does photosynthesis take place
- chloroplasts
thylakoid
- membrane structure where light energy is converted to chemical energy
- that energy is released into the surrounding liquid (stroma), then is turned into sugar
light energy
- type of kinetic energy made of photons
- photons are organized into waves
- wavelength corresponds to the amount of energy being carried out by the photon
pigments
- molecules that absorb light
chlorophyll
- main pigment molecule in plants that absorbs light energy from the sun
opsin
proteins that allow us to see color differently
NAD
high energy electron carrier
ATP + NAD synthesis
ATP + NAD + carbon dioxide go through the calvin cycle –> sugar
calvin cycle
- the enzyme rubisco picks carbon atoms from CO2 molecules in the air & attaches them to an organic molecule
- the organic molecule is modified into a small sugar called G3P (using energy from ATP & NADPH)
- some molecules of G3P are used to regenerate the original organic molecule, using ATP
most prevalent protein on the planet
rubisco
cellular respiration equation
oxygen + sugar + water –> ATP
genome
an organisms complete set of DNA (mito. or chloro AND nucleus DNA)
chromosomes
- one+ unique pieces of DNA
gene
- specific sequence of DNA that carries info necessary for producing a functional product
- contains instructions for cells
locus
- position of a gene on a chrosome
alleles
different versions of a gene that code for the same feature *expression
trait
- any single characteristic/feature of an organism *seeing the expression of the allele
introns
noncoding regions within genes (25%)
intervening region
genotype
- genes that an organism carries for a particular trait
- what is *encoded in that stretch of DNA
phenotype
- physical manifestation of gene for a particular trait
- what actually ends up being *expressed
transcription:
- GOAL: produce mRNA from copying a DNA sequence
1. promoter brings DNA sequence and RNA polymerase to begin
2. Transcribe (AU/GC) & termination signal
3. special nucleotide is placed as cap on end of RNA
4. tail is place on other end of RNA = 200 adenines “poly A tail” for protection
translation:
- GOAL: take mRNA made in transcription and make it into a protein
1. tRNA anticodon reads 3 nucleotides at a time
2. codon decides which amino acids go in
3. ribosomes attach to right triplet
4. new amino acid added to polypeptide chain
5. exit site = ribosomes fall off last triplet
== completed protein
gene regulation
- whether a gene is turned off or on
- does the gene produce a protein
point mutations
- nucleotide substitution / insertion / deletion
chromosomal mutation
- chromosome deletion / relocation / duplication
spontaneous DNA
occurs on accident during replication
genetic engineering
- manipulation of organisms’ genetic material by adding, deleting, or transplanting genes from one organism to another
- used in agriculture, health, & forensic science
DNA chopping
- foreign DNA is isolated and chopped by enzymes
- specific sequences (palindromes) removed
- this creates sticky dens = single DNA strand that will find a matching sequence
DNA amplifying
- polymerase chain reaction (PCR)
- DNA strands are heated = strands seperate
- strands are cooled down & synthesized
- primer is attached
- results in 2 identical copies of original segment of DNA
DNA insertion
- bacterial plasmid carried info/enzymes
- cut a plasmid w/ restriction enzyme
- gene of interest is inserted into plasmid
- segments now share bases & fit together
- this is cloning
DNA growth
- large amounts of DNA create gene library
- each piece is inserted into plasmid
- plasmid is introduced to different bacterial cell
- bacteria are allowed to divide repeatedly, each producing a clone of foreign DNA fragment
human growth hormone
- produced by pituitary gland
erythropoietin
- produced by kidneys
- RBC production
telomeres
- sections of noncoding, repetitive DNA
- act as protective cap on the tip of each chromosome
binary fission
- replication = creates a duplicate of each chromosome
- parent cell divides to create 2 daughter cells
- asexual reproduction
eukaryotic cell cycle:
- gap 1 = cell’s primary growth phase
- some cells enter G0 (resting phase outside of cell)
- gap 2 = second period of growth & prep for cell division
- mitosis = parent cell’s nucleus, w/ duplicated chromosomes, divides
- cytokinesis = cytoplasm is divided into 2 daughter cells, each has complete set of parent cell’s DNA
cell cycle control system:
3 primary checkpoints that regulate cell cycle in eukaryotes
1. G1IS = is DNA damaged/does it have sufficient nutrients?
2. G2IM = begins during synthesis, has DNA replicated properly?
3. spindle assembly = begins during mitosis, are spindle fibers properly build & attached
=== checks that chromosomes are set to go to the right place
DNA replication main enzymes & their functions:
- DNA helicase unwinds the double helix
- DNA polymerase synthesizes replacement of DNA & adds onto growing polymer
*always adding on 3 prime end
apoptosis
cell suicide
mitosis (IPMAT)
- interphase = chromosomes replicate in prep. for mitosis
- prophase = sister chromatids condense / spindle forms
- metaphase = sister chromatids line up @ center of cell
- telophase = terminal stage
- cytokinesis = cytoplasm divides into 2 daughter cells
what is cancer:
- unrestrained cell growth
- occurs when disruption of DNA interferes with cell’s ability to regulate cell division
- error in cell cycle (no G0 phase)
metastasis
- cancer cells spread to other cell in body via circulatory & lymphatic systems
meiosis
- sexual reproduction
- reduces genetic material in gametes & produces gametes that differ
- takes place in gonads (egg & sperm)
diploid
cells that have 2 copies of each chromosome
haploid
meiosis enables organisms to produce haploid gametes (single set of chromosomes)
meiosis division rounds:
division 1: homologues separate = IPMAT1
division 2: IPMAT 2
difference between meiosis & mitosis:
- between interphase & prophase
- as chromosomes condense down, the homologues find each other & perform recombination (crossing over)
chiasmata
actual point where the chromosomes cross over
sexual reproduction
females = XX
males = XY
down syndrome
- extra copy of chromosome 21 (3 total copies)
trisomy
3 copies of a chromosome
turner syndrome (female)
- one x chromosome
- short height
- web skin between neck & shoulders
- underdeveloped ovaries
- learning difficulties
Klinefelter syndrome (male)
- XXY chromosomes
- underdeveloped testes
- lower testosterone
- development of some female features
- long limbs, slightly taller than average
XYY male
- taller than average
- moderate to severe acne
- intelligence may be slightly lower than average
- “super males”
XXX female
- may be sterile
- no obvious physical or mental problems
- “metafemales”
heredity
passing of characteristics from parent to offspring through parent’s genes
single-gene traits
- some traits are determined by instructions an organism carries on one gene
- *most human characteristics are influenced by multiple genes + environment
codominance of genes:
heterozygous individual shows features of both alleles
Ex: blood type
incomplete dominance of genes:
- phenotype of a heterozygote is intermediate between the phenotypes of two homozygotes
antigens
- signposts in the body’s immune system
- illicit’s immune response
antibodies
immune system molecules in the bloodstream that attack foreign invaders
(self recognition)
polygenic traits
- influenced by many different genes
pleiotropy
- one gene influences multiple, unrelated genes
- ex: siamese cat
sex-linked traits
- carried on X chromosome
- differ in expression in males & females
- ex: males tend to be colorblind more often than females due to only have 1 X chrom.
evolution
- changes in allele frequencies of a population over time
- populations evolve
genetic drift
- frequency of alleles undergo a random change, unrelated to the allele’s influence on reproductive success
- BIGGEST influence on evolution
urey-miller experiment
- flask with water, H2, CH4(methane), and NH3(ammonia)
- ## 5 amino acids formed
