Biology Final Exam Vocabulary

Cells

are the basic units of life

cell(plasma) membrane

all cells are surrounded by a thin flexible barrier

nucleus

a large membrane enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities

eukaryote

are cells that enclose their DNA in nuclei

prokaryote

are cells that do not enclose DNA in nuclei

organelle

structures that act like specialized organs(literally “little organs”)

cytoplasm

the portion of the cell outside the nucleus

cell wall

many cells, including most prokaryotes, also produce a strong supporting layer around the membrane

phospholipid bilayer or lipid bilayer

gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroundings

selectively permeable

most biological membranes are selectively permeable meaning that some substances can pass across them and others cannot (also called semipermeable membranes)

vacuoles

store materials like water, salts, proteins, and carbohydrates

lysosomes

small organelles, break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell (also involved in breaking down organelles that have outlived their usefulness

cytoskeleton

network of protein filaments, helps the cell maintain its shape and is also involved in movement

centrioles

are located near the nucleus and help organize cell division

ribosome

proteins are assembled on ribosomes, they are small particles of RNA and protein found throughout the cytoplasm in all cells

ER-endoplasmic reticulum

internal membrane system, where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell

golgi apparatus

proteins produced in the rough ER move next into an organelle

chloroplasts

the biological equivalents of solar power plants, they capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis

mitochondria

the power plants of the cell, they convert the chemical energy stored in food into compounds that are more convenient for the cell to use

passive transport

the movement of materials across the cell membrane without using cellular energy is called passive transport

diffusion

the driving force behind the movement of many substances across the cell membrane

facilitated diffusion

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

aquaporins

water channel proteins

osmosis

the diffusion of water through a selectively permeable membrane

isotonic

means “same strength” note that “strength” refers to the amount of solute, not water

hypertonic

“above strength”, the more concetrated sugar solution

hypotonic

the dilute sugar solution or “below strength”

osmotic pressure

driven by differences in solute concetration, the net movement of water out of or into a cell produces a force

active transport

the movement of materials against a concentration difference

endocytosis

the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane

exocytosis

many cells also release large amounts of material

phagocytosis

a type of endocytosis, in which extensions of cytoplasm surround a particle and package it within a food vacuole

pinocytosis

many cells take up liquid from the surrounding environment, tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell

contractile vacuoles

the removal of water by means of a contractile vacuole is one example of this kind of active transport

homeostasis

to maintain homeostasis, unicellular organisms grow, respond to the environment, transform energy and reporduce

tissue

a group of similar cells that performs a particular function

organ

many groups of tissues work together

organ system

a group of organs that work together to perform a specific function

receptor

on or in a cell a specific protein to whose shape fits that of a specific molecular messenger, such as a hormone

adenosine triphosphate (ATP)

one of the most important compounds that cells use to store and release energy

heterotroph

organisms that obtain food by consuming other living things

autotrophs

organisms that make their own food

photosynthesis

the process by which autotrophs use the energy of sunlight to produce high-energy

carbohydrates

sugar and starches- that can be used as food

pigment

light-absorbing molecules that plants use to gather the sun’s energy

chlorophyll

the plant’s principal pigment

chloroplast

photosynthesis takes place inside organelles

thylakoid

chloroplasts contain an abundance of sac-like photosynthetic membranes

stroma

the fluid portion of the chloroplast, outside of the thylakoids

grana(granum)

thylakoids are interconnected and arranged in stacks

NADP+

carrier molecule that is a compound

light-dependent reactions

first set of reactions, they require the direct involvement of light and light-absorbing pigments, they use energy from sunlight to produce energy-rich compounds such as ATP

light-independent reactions(Calvin cycle)

ATP and NADPH molecules produced in the light-dependent reactions are used to produce high-energy sugars from carbon dioxide, no light is required to power

calorie

amount of energy needed to raise the temperature of 1 gram of water 1 degree celsius

cellular respiration

the process that releases energy from food in the presence of oxygen

aerobic

pathways of cellular respiration that require oxygen (“in air”)

anaerobic

does not require air (“without air”)

mitochondrion

cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use

glycolysis

1 molecule of glucose, a 6-carbon compound, is transformed into 2 molecules of pyruvic acid, a 3-carbon compound

NAD+

an electron carrier

krebs cycle

pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

matrix

the innermost compartment of the mitochondrion and the site of the Krebs cycle reactions

electron transport cycle

uses the high-energy electrons from glycolysis and the Krebs cycle to convert ADP to ATP

fermentation

releases energy from food molecules by producing ATP

alcoholic fermentation

used to produce alcoholic beverages, produces ethyl alcohol and carbon dioxide

lactic acid fermentation

regenerates NAD+ so that glycolysis can continue, does not give off carbon dioxide

transformation

one type of bacteria (the harmless form) had been changed permanently into another (the disease-causing form)

bacteriophage

a kind of virus that infects bacteria

DNA(deoxyribonucleic acid)

genetic material that organisms inherit from their parents

nucleic acid

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

nitrogenous bases

bases that contain nitrogen

base pairing

principal bonds in DNA can form only between adenine and thymine and between guanine and cytosine

nucleotide

subunit of which nucleic acids are composed; made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

double helix

explains chargaffs rule of base pairing and how the two strands of DNA are held together, can tell us how DNA can function as a carrier of genetic information

genes

sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parent to offspring

antiparallel

in the double helix model the two strands of DNA run in opposite directions

hydrogen bonds

weak attraction between a hydrogen atom and another atom

covalent bonds

type of bond between atoms in which the electrons are shared

replication

process of copying DNA prior to cell division

DNA polymerase

an enzyme that joins individual nucleotides to produce a new strand of DNA

telomere

the tips of a eukaryotic chromosome

helicase

an enzyme that unzips the DNA molecule

semi-conversation replication

one strand of DNA is original, the other strand is new

RNA(ribonucleic acid)

a nucleic acids that consists of a long chain of nucleotides

messenger RNA

the RNA molecules that carry copies of these instructions

ribosomal RNA

type of RNA that combines with proteins to form ribosomes

transfer RNA

type of RNA that carries each amino acid to a ribosome during protein synthesis

transcription

synthesis of an RNA molecule from a DNA template

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template

promoter

specific region of a gene where RNA polymerase can bind and begin transcription

intron

sequence of DNA that is not involved in coding for a protein

exon

expressed sequence of DNA; codes for a protein

polypeptide

long chains of amino acids that makes proteins

amino acid

compound with an amino group on one end and a carboxyl group on the other end

genetic code

collection of codons of mRNA each of which directs the incorporation of a particular amino acid into a protein during protein synthesis

codon

group of three nucleotide base in mRNA that specify a particular amino acid to be incorporated into a protein

anticodon

group of three bases on a tRNA molecule that are complementary to the three bases of a codon of mRNA

translation

process by which the sequence of bases of an mRNA is converted into the sequence of amino acids of a protein

gene expression

process by which a gene produces its product and the product carries out its function

ribosome

cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell; the site of protein synthesis