Bio Exam

Organelles

Internal functional structures of a cell

Plasma membrane

A dynamic barrier that surrounds the cytosol of the cell

Nucleus

An organelle that contains almost all DNA in a eukaryotic cell

Nuclear envelope

Two lipid bilayers folded together that enclose the nucleus

Mitochondria

An organelle with two membranes; the site of most ATP synthesis during aerobic cellular respiration

Plastids

A membrane-bound organelle that is involved in photosynthesis and storage in plants and algae

Chloroplasts

A double-membrane-bound organelle that contains enzymes and pigments that are used to perform photosynthesis in eukaryotic cells

Cytoskeleton

A dynamic system of filaments that provides cell structure, helps with cell division, and enables the cell and inner organelles to move around

Cell wall

The outer barrier of a plant cell; surrounds cell membrane and provides structural support

Extracellular matrix (ECM)

A molecular system that supports and protects a cell

Cellular respiration

A process where mitochondria synthesize ATP

Citric Acid Cycle

A metabolic cycle where acetyl groups are oxidized to CO2, producing ATP and electron carriers

Acetyl-CoA

A molecule that enters the citric acid cycle, formed from pyruvate

Messenger RNA (mRNA)

The end product of the transcription of a gene; translated by ribosomes into a protein

Transfer RNA (tRNA)

A carrier molecule that binds to a specific amino acid and adds it to a growing polypeptide chain

Ribosomal RNA (rRNA)

An RNA molecule within the ribosome that bonds the correct amino acid to the polypeptide chain

RNA polymerase

An enzyme that reads a DNA strand and creates a complementary strand of RNA

Template strand

The complementary base pair of the coding strand, read by RNA polymerase

Transcription

The process where RNA polymerase reads a DNA strand and creates a complementary strand of RNA

Translation

The process where mRNA associates with a ribosome, and amino acids are linked to create a protein

One gene–one enzyme hypothesis

The hypothesis that each gene is unique and codes for the synthesis of a single enzyme

Negative feedback

A process where the effects of a mechanism slow or stop the mechanism

Sensor

A component of a feedback system that detects changes in the internal environment

Integrator

A component of a feedback system that sorts and interprets neural messages

Setpoint

The target value of a physiological variable in a feedback system

Effector

A component of a feedback system that carries out the response

Restriction enzymes

Enzymes that chop DNA at specific sequences to protect prokaryotic cells from viruses

Blunt end

The end that remains after restriction enzymes cut straight across a DNA strand

Sticky end

The end that remains after restriction enzymes cut on a zigzag across a DNA strand

DNA ligase

An enzyme that joins cut strands of DNA

Plasmids

Small circular pieces of DNA that are found in bacteria and replicate independently of chromosomal DNA

Competent cell

A cell that is able to take up foreign DNA from its surroundings

Vector

A DNA molecule that is used as a vehicle to transfer foreign genetic material into a cell

Transformation

The successful introduction of DNA from another source into a cell

Hybridization probe

A fragment of DNA that is used to detect the presence of complementary nucleotide sequences

Chloroplast

Organelle where photosynthesis occurs, containing three membranes and distinct spaces

Thylakoid membranes

Interconnected stacks of flattened discs where light-dependent reactions occur

Stroma

Fluid within the inner membrane of a chloroplast, where the Calvin cycle occurs

Photosystem

Organized pigment proteins that absorb light energy

Protons

Positively charged subatomic particles that determine the identity of an atom

Neutrons

Neutral subatomic particles found in the nucleus of an atom

Electrons

Negatively charged subatomic particles that occupy orbitals around the nucleus

Isotope

An atom of an element with the same number of protons but a different number of neutrons

Hydrolysis reactions

A chemical reaction in which water is used as a reactant to split a larger molecule into smaller subunits

Redox Reactions

Reactions where electrons are lost from one atom and gained by another

Oxidation

A reaction in which a molecule loses electrons

Reduction

A reaction in which a molecule gains electrons

Afferent neuron

A neuron that carries impulses from sensory receptors to the central nervous system (also called a sensory neuron)

Interneuron

A local circuit neuron of the central nervous system that relays impulses between afferent and efferent neurons

Efferent neuron

A neuron that carries impulses from the central nervous system to skeletal muscles (also known as a motor neuron)

Dendrites

Highly branched projections that receive signals and transmit them toward the cell body

Axon

Specialized projections that conduct signals away from the cell body to another neuron or an effector

Axon terminals

Small, button-like swellings on the end of an axon that act as the points of connection that enable the signals to be transmitted

Glial cell

A non-conducting cell that is important for the structural support and metabolism of nerve cells

Myelin sheath

Tightly wrapped layers of plasma membrane formed from Schwann cells; act as electrical insulators due to high lipid content

Nodes of Ranvier

Gaps between Schwann cells; expose axon membrane to ECF

Reflex arc

Simplest neural circuit that travels through the spinal cord but does not require the coordination of the brain; allows for reflex actions

Glycolysis

The breakdown of glucose into two molecules of pyruvate

Pyruvate oxidation

The process where pyruvate is converted into acetyl-CoA

Polymerase Chain Reaction (PCR)

A process that is used to make a huge number of copies of a DNA sequence in a laboratory

DNA primer

A short single-stranded DNA sequence, easily synthesized in a laboratory, that is complementary to a sequence at one end of the target sequence

Gel electrophoresis

A method for separating large molecules, such as DNA, RNA, and proteins

Structural genomics

The study of the structure of genes and their locations in a genome

Functional genomics

The study of the functions of genes, the proteins they make, and how these proteins function

Bioinformatics

The use of computer technology to process a large amount of biological data

DNA microarray

A solid surface that has a microscopic grid of many DNA fragments attached, used to determine gene expression and function

Poly(A) tail

A chain of adenine nucleotides that are added to the 3’ end of the pre-mRNA molecule to protect it from enzymes in the cytosol

Alternative splicing

A process where some introns are considered exons, and exons are considered introns, resulting in multiple different related proteins from pre-mRNA

Fluid Mosaic Model

The idea that a biological membrane consists of a fluid phospholipid bilayer, in which proteins are embedded and float freely

Peripheral membrane protein

A protein on the surface of the membrane

Synapse

A functional connection between neurons or between neurons and effectors

Chemical synapse

A synapse in which a neurotransmitter moves from a presynaptic cell to a postsynaptic cell through the synaptic cleft

Neurotransmitter

A chemical that is released from vesicles into synapses to facilitate nerve signal transmission

Electrical synapse

A synapse in which the presynaptic cell makes direct contact with the postsynaptic cell, allowing current to flow via gap junctions between the cells

Action potential

The voltage difference across a nerve cell membrane when the nerve is excited

Photosystem II

A photosystem that splits water into electrons, protons, and oxygen

P680

The chlorophyll a molecule in the reaction center of Photosystem II

Pituitary gland

A two-lobed gland within the cranial cavity that produces hormones that control the other endocrine glands

Tropic hormones

Hormones secreted by the anterior pituitary gland that control endocrine glands elsewhere in the body

Torpor

A short-term state of reduced metabolic rate and body temperature

Hibernation

A state of greatly reduced metabolic rate and activity that enables an animal to survive the winter

Autoionization

The process in which a molecule spontaneously dissociates into ions

Buffer

A chemical that compensates for pH changes in a solution by accepting or donating H+ ions

ATP synthase

A structure that spans the inner mitochondrial membrane and synthesizes ATP using the H+ gradient

Carbon fixation

The conversion of carbon from an inorganic to an organic form

RuBisCO

An enzyme that catalyzes the reaction of RuBP with CO2 in the Calvin cycle

Insulin

A hormone that promotes the uptake of glucose by cells

Glucagon

A hormone that stimulates the breakdown of glycogen to increase blood glucose levels

Grey matter

The tissue of the brain and spinal cord where the cell bodies and dendrites of neurons are located

White matter

The tissue of the brain and spinal cord, composed primarily of axons of neurons

Medulla oblongata

The hindbrain region that connects the spinal cord to the cerebellum; important in autonomic nerve control

Cerebellum

The hindbrain region that is involved in muscle movement and balance

Cerebrum

The forebrain; the brain region that is involved in motor activities and sensory information

Cerebral cortex

The outermost layer of the cerebral hemisphere

Hypothalamus

A small conical area in the brain that regulates basic homeostatic functions

Basal nuclei

Grey-matter centers that surround the thalamus on both sides of the brain and moderate voluntary movements

Blood-brain barrier

A barrier formed by tight junctions between endothelial cells in the capillaries in the brain that blocks the movement of most substances into the brain via the bloodstream

Nephron

The functional unit of the kidney

Proximal convoluted tubule

The duct portion of a nephron that connects the Bowman’s capsule to the loop of Henle

Loop of Henle

The U-shaped part of the duct that connects the proximal convoluted tubule to the distal convoluted tubule