Honors Bio Midterm

science

an organized way of gathering and analyzing evidence about the natural world

scientific method

the heart of science; 5 steps: observing and asking questions, making inferences and forming hypotheses , conducting controlled experiments, collecting and analyzing data, drawing conclusions

hypothesis

a scientific explanation for a set of observations that can be tested in ways that support or reject it; when enough experimental data support a hypothesis, the hypothesis becomes a theory

seven characteristics of living things

1. all living things are made of cells
2. obtain and use materials and energy
3. grow, develop, and can reproduce
4. maintain a stable internal environment (homeostasis)
5. universal genetic code (DNA/RNA)
6. respond to the environment
7. evolve as a group (smallest group that can evolve is a population)

population

a group of the same species living in the same area

three subatomic particles

protons (+), neutrons (0), electrons (-)

atomic number

the amount of protons in the nucleus

atomic mass

the weighted average of an elements isotopes

mass number

rounded atomic mass; protons + neutrons

isotopes

atoms with the same amount of protons but different amount of neutrons

ionic compounds

metal + nonmetal, electrons are TRANSFERRED (NaCl)

covalent compounds

nonmetal + nonmetal, electrons are SHARED (H2O)

valance electrons

electrons in the outermost shell

covalent bonds

occurs when valance electrons are SHARED by two atoms

nonpolar covalent bonds

electrons are shared EQUALLY between two atoms

electronegativity

a tendency to attract electrons of a covalent bond

polar covalent bonds

one atom has greater electronegativity than the other, results in an UNEQUAL sharing of the electrons

Ionic bonds

bonds where two atoms attract valance electrons so unequally that the more electronegative atom steals the electron away from the less electronegative atom; an ion is the resulting charged atom or molecule

cation

positive, metals, loses electrons (-), first in an ionic compound

anions

negative, nonmetals, gains electrons (+), second in an ionic compound

hydrogen bonds

relatively weak bonds that from between the partial positively charged hydrogen atom of one molecule and the strongly electronegative oxygen or nitrogen of another molecule; the key to all properties of water and what makes water so unique

chemical reaction

shows the reactants which are the starting materials, an arrow to indicate their conversion into the products, the ending materials

cohesion

an attraction between molecules of the same substance

adhesion

an attraction between molecules of different substances

why does ice float?

as water freezes, each molecule forms stable hydrogen bonds with its neighbors, holding them at “arms length” and creating a 3D crystal. ice crystals have fewer molecules than liquid water, therefore ice is less dense and floats on top of liquid water

solution

a liquid consisting of a uniform mixture of two or more substances

solvent

the dissolving agent; water is the solvent of life

solute

the substance that is dissolved

aqueous solution

a solution in which water is the solvent, water’s versatility as a solvent results from the polarity of its molecules

pH scale

measures the concentration pf hydrogen ions in a solution, the scale ranges from 0-14, pure water has a pH of 7

acidic solutions

have pH values below 7

basic or alkaline solutions

have pH values above 7

organic chemistry

the study of compounds with bonds between carbon atoms; CHONP

carbohydrates

monomers: monosaccharides, examples: glucose, fructose, cellulose, chitin, starch, functions: short term energy storage

proteins

monomers: amino acids, examples: enzymes, hormones, functions: structural support cell signaling and communication

lipids

monomers: triglycerides, examples: fats, oils, waxes, phospholipids, functions: long term insulation, membrane lipids

nucleic acids

monomers: nucleotides, examples: DNA, RNA, functions: store and transmit genetic information

timeline of cell discoveries

1665- Hooke discovers and names cells in thin slices of cork, 1676- Van Leeuwenhoek discovers protozoa by looking at pond water; first to see living cells under a microscope, 1831- Brown discovers and names the nucleus of the cell, 1838-39- Schleiden (plant) and Schwann (animal) theorize that all living things are made of cells, 1855- Virchow theorized that new cells are produced from existing cells

why are cells small?

as the radius of a cell increases, its surface area increases as the square of its radius, but its volume increases as the cube of its radius (much more rapidly). therefore, as a cell increases in size, its surface area-to-volume ratio decreases

prokaryotic cells

the microorganisms placed in domains Bacteria and Archaea consist of prokaryotic cells (prokaryotes); cells that do not have a nucleus but instead a nucleoid which is a region where the cell’s DNA is located (not enclosed by a membrane); prokaryotic cells are structurally simpler than eukaryotic cells

eukaryotic cells

all other forms of life are placed in domain Eukarya (eukaryotes); these cells have a membrane enclosed nucleus, which houses most of their DNA, and many membrane bound organelles that perform specific functions

cell theory

1. all things are made of cells
2. cell are the basic unit of structure and function in living things
3. new cells are produced from existing cells

organelles

small structures inside a cell that are surrounded by a membrane and have a specific function.

nucleus

contains the cell’s genetic instructions encoded in DNA; serves as as the control center for cell metabolism and reproduction (ribosome factory)

ribosomes

if the nucleus is the command center, then ribosomes are the machines that carry out those commands. ribosomes are the cellular components that use instructions from the nucleus written in mRNA, to build proteins; sites of protein synthesis

endoplasmic reticulum (ER)

the ER is an extensive network of flattened sacs and tubules, it is a prime example of the direct and indirect interrelatedness of parts of the endomembrane system; serves as a pathway for the transport of materials throughout the cell, also associated with synthesis and storage

smooth ER

outer surface lacks ribosomes; functions in a variety of metabolic processes; stores calcium ions

rough ER

has bound ribosomes that stud the outer surface of the membrane ,appears rough,; many types of cell secrete proteins produced by ribosomes attached to rough ER, the rough ER is also involved with the production, folding, quality control and dispatch of some proteins

Golgi apparatus

modifies, sorts, and ships cell products; the Golgi serves as a molecular warehouse and processing station for products manufactured by the ER

lysosomes

a membrane-enclosed sac of digestive enzymes, lysosomes have several types of digestive functions; also serve as recycling centers

vacuoles

large vesicles that have a variety of functions; fluid filled organelles enclosed by a membrane; contains stored food or wastes

mitochondria

the powerhouse of the cell; organelles that carry out cellular respiration in nearly all eukaryotic cells; mitochondria use O2 and release CO2 in transforming the chemical energy of foods to a form (ATP) that can be used for cellular work

chloroplasts

site of photosynthesis; carries out complex multi-step processes; enclosed by an inner and outer membrane separated by a thin internal membrane space

cilia

hairlike structures with the capacity for movement

flagella

a long, hairlike structure used for movement; propel a cell through its liquid environment

cell wall

gives the cell its shape and provides protection; not found in animal cells only plant

cell membrane

AKA plasma membrane, regulates what comes in and out of the cell; made up of the phospholipid bilayer

hydrophilic

water attracting; the phospholipid head is hydrophilic

hydrophobic

water repelling; the two phospholipid tails are hydrophobic

carbohydrate chains

cells are able to recognize various molecules and other types of cells with the carbohydrate chains

integral proteins

helps transport materials (such as glucose) across the cell membrane

peripheral proteins

involved in cell to cell recognition

cholesterol

helps maintain the flexibility of the membrane

passive transport

does not require energy; an example of passive transport is diffusion, the process by which particles move from an area of high concentration to an area of lower concentration

active transport

the movement of materials against a concentration difference; requires energy

osmosis

the facilitated diffusion of water through a selectively permeable membrane

facilitated diffusion

the process by which molecules that cannot directly diffuse across the membrane pass through special protein channels

hypertonic solution

(water leaves the cell) there is more M OUTSIDE the cell; plant cells: plasmolysis occurs, the plasma membrane pulls away from the cell wall,

animal cells: shrinks (losing water)

isotonic solution

(water enters and leaves the cell equally)

plant cells: start to wilt

animal cells: normal

hypotonic solution

(water enters the cell) more M INSIDE the cell;

plant cell: normal (has turgor pressure)

animal cell: can burst, will swell (lysis)

molarity

used to express the concentration of a solution, how concentrated or diluted; moles of a solute over liters of a solution

M

molar

ATP

adenosine-triphosphate, made of of adenine, ribose a 5 carbon sugar, and 3 phosphate groups; ATP is the source of energy for use and storage in cells

cell cycle

a series of events (including mitosis) that take place in a cell as it grows and divides (end results= two identical daughter cells)

G1 phase

cell grows larger and makes proteins and organelles needed for DNA synthesis

S phase

DNA synthesis occurs, where DNA is copied

G2 phase

organelles and proteins necessary for cell division grow in preparation for mitosis

M phase

nuclear division (mitosis) occurs, followed by cytoplasmic division (cytokinesis)

mitosis

prophase, anaphase, metaphase, telophase; NOT cytokinesis; PMAT

interphase

periods of growth between cell divisions (G1,S,G2)

prophase

DNA condenses from chromatin

metaphase

chromosomes line up on the metaphase plate

anaphase

sister chromatids move to opposite ends of the cell

telophase

nuclear membrane forms around chromosomes

cytokinesis

separation of the cytoplasm, results in two identical cells

photosynthesis

carbon dioxide + water --light→ glucose + oxygen

6CO2 + 6H2O --light→ C6H12O6 + 6O2

takes place in the chloroplast

stages of photosynthesis

light independent reactions(Calvin Cycle): do not require direct sunlight, take place outside the thylakoids, in the stroma; produce ADP and NADP+ and put it back into light dependent rxns

light dependent reactions: require direct sunlight, take place in the thylakoid membranes; produce ATP and NADPH

thylakoids

saclike chlorophyll-containing membranes

granum

thylakoids that are interconnected and arranged in stacks

stroma

the fluid portion of the chloroplast, outside of the thylakoids

autotrophs

organisms that make their own food/energy; go through photosynthesis

heterotrophs

organisms that cannot make their own food; dependent on autotrophs as an energy source

cellular respiration

6O2 + C6H12O6 → 6CO2 + 6H2O + energy

oxygen + glucose → carbon dioxide + water + energy

what is the relationship between photosynthesis and cellular respiration?

photosynthesis put backwards is cellular respiration and vise versa; photosynthesis removes carbon dioxide from the air, and cellular respiration puts it back

anaerobic

pathways of cellular respiration that do not use oxygen

aerobic

pathways of cellular respiration that require oxygen

glycolysis

glucose first enters a chemical pathway known as glycolysis, only about 10 percent of its energy is captured to produce ATP during this stage; occurs in the cytoplasm; enzymes split a molecule of glucose into two molecules of pyruvate, which releases energy that is transferred to ATP; 2 ATP molecules

Krebs (citric acid cycle)

energy stored in pyruvate is transferred to NADH and FADH2, and some 36 molecules ATP is produced with the help of glycolysis

oxidative phosphorylation

energy is harnessed through a series of protein complexes embedded in the inner-membrane of mitochondria (called the electron transport chain and ATP synthase) to create ATP

how does ATP drive cellular work; how cells transform energy and matter

the ATP molecule splits off one of its three phosphate groups, becoming ADP + a phosphate group