Biology STAAR review

Amino Acid

Amino acids are molecules that combine to form proteins.

Biomolecules

Biomolecules are an organic molecule that includes carbohydrates, protein, lipids, and nucleic acids.

Carbohydrates

a large group of organic compounds that includes sugars, starch, and cellulose, containing Hydrogen, Oxygen, and water also used as structural materials and for energy storage within living tissues

Enzymes

a substance that acts as a catalyst in living organisms and regulate the rate of chemicals proceeding

Fatty acids

a carboxylic acid consisting of a hydrocarbon chain and a terminal carboxyl group in fats and oils

Glucose

Glucose is the main type of sugar in the blood and is the major source of energy for the body's cells.

Glycerol

a simple triol compound colorless, odorless, viscous liquid that is sweet-tasting and non-toxic.

Lipids

Lipids are organic compounds like fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. 

Monomer

atoms or small molecules that bond together to form more complex structures such as polymers.

Monosaccharides

any of the class of sugars  that cannot be hydrolyzed to give a simpler sugar.

Nucleic acids

complex organic substance present in living cells, especially DNA or RNA ; molecules consist of many nucleotides in a long chain.

Nucleotides

A nucleotide consists of a sugar molecule attached to a phosphate group and a nitrogen-containing base.

Polymer

a substance consisting of very large molecules called macromolecules: are composed of many repeating subunits called monomers ; Play essential role in life.

polysaccharide

a carbohydrate whose molecules consist of a number of sugar molecules bonded together.

Proteins

A protein is a naturally occurring, complex substance that consists of amino acid joined by peptide bonds.

Products

Products formed from chemical reactions. reactants are transformed into products after passing through a high energy transition state. process results in consumption of the reactant. 

Substrate

is a molecule that an enzyme reacts with. 

Cell

The basic structural, functional, and biological unit of all living organisms.

Cell Theory

A fundamental theory in biology stating that all living things are composed of cells, cells are the basic unit of life, and all cells come from pre-existing cells.

Nucleus

A membrane-bound organelle in eukaryotic cells that contains genetic material (DNA) and controls cellular activities.

Eukaryote

An organism made up of cells that have a nucleus enclosed within membranes.

Prokaryote

A unicellular organism that lacks a membrane-bound nucleus and other membrane-bound organelles.

Cytoplasm

The jelly-like substance within the cell membrane that contains the organelles and is the site of most cellular processes.

Organelle

Specialized structures within a cell that perform specific functions (e.g., mitochondria, ribosomes).

Ribosome

A small structure found in all cells that assembles proteins from amino acids.

Endoplasmic Reticulum (ER)

A network of membranes in the cell that helps in the production and transport of proteins (rough ER) and lipids (smooth ER).

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.

Vacuole

A membrane-bound sac within the cell used for storage of materials like water, nutrients, or waste.

Lysosome

An organelle containing digestive enzymes used to break down waste materials and cellular debris.

Cytoskeleton

A network of protein filaments and tubules that gives the cell its shape, supports movement, and helps transport materials.

Chloroplast

An organelle found in plant cells where photosynthesis occurs, converting light energy into chemical energy.

Mitochondrion

The "powerhouse" of the cell; an organelle that produces energy (ATP) through cellular respiration.

Cell Wall

A rigid outer layer found in plant, fungi, and some bacterial cells that provides structure, support, and protection.

Cell Membrane

A flexible, semi-permeable membrane surrounding the cell that controls what enters and exits the cell.

Homeostasis

The process by which a cell or organism maintains a stable internal environment despite changes in external conditions.

Diffusion

The movement of particles from an area of higher concentration to an area of lower concentration.

Facilitated Diffusion

The passive movement of molecules across a cell membrane through protein channels or carriers, without using energy.

Osmosis

The diffusion of water across a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Isotonic

A solution with the same concentration of solutes as the cell, resulting in no net movement of water.

Hypertonic

A solution with a higher concentration of solutes than the cell, causing water to leave the cell and the cell to shrink.

Hypotonic

A solution with a lower concentration of solutes than the cell, causing water to enter the cell and the cell to swell.

Osmotic Pressure

The pressure created by the movement of water through osmosis; it can cause cells to swell or shrink depending on the surrounding solution.

transport proteins

form channels and pumps to help move materials across the membrane

receptor proteins

 recognize and bind substances at the cell surface, forming a method of communication between the cell and external environment

Passive Transport

is the movement of substances across a cell membrane without the use of energy

Diffusion

is the spreading out of molecules from a region of high concentration to a region of low concentration.

Facilitated Diffusion

Facilitated diffusion is a type of passive transport used for molecules that do not readily diffuse through membranes. 

These molecules may be polar (water and glucose) and cannot diffuse through the lipid layer.

Other molecules are too large to pass through pores in the membrane  

Endocytosis

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

The pocket that results breaks loose from the cell membrane and forms a vesicle within the cytoplasm.

Large molecules and clumps of food are taken up this way.

This requires energy from the cell.

Phagocytosis

the engulfing of large particles

Pinocytosis

“cell drinking” 

The cell surrounds and engulfs droplets of extracellular fluid

Exocytosis

is the release of large materials from the cell 

A vesicle fuses with the cell membrane, forcing the contents out of the cell.

ATP (Adenosine Triphosphate)

The main energy-carrying molecule used by cells to power their functions.

Heterotroph

An organism that cannot make its own food and must obtain energy by consuming other organisms.

Autotroph

An organism that produces its own food using light or chemical energy, like plants and some bacteria.

Photosynthesis

The process by which autotrophs (like plants) use sunlight, carbon dioxide, and water to produce glucose and oxygen.

Calorie

A unit of energy; specifically, the amount of energy needed to raise the temperature of 1 gram of water by 1°C.

Cellular Respiration

The process by which cells break down glucose and other food molecules to produce ATP, using oxygen.

Glycolysis

The first step of cellular respiration, occurring in the cytoplasm, where glucose is broken down into pyruvate, producing a small amount of ATP.

Krebs Cycle (Citric Acid Cycle)

The second stage of cellular respiration that takes place in the mitochondria and produces energy-rich molecules (like NADH and FADH₂).

Electron Transport Chain (ETC)

The final stage of cellular respiration where high-energy electrons are used to produce a large amount of ATP in the mitochondria.

ATP Synthase

An enzyme that helps produce ATP by using the energy from hydrogen ion flow during the electron transport chain.

Fermentation

An anaerobic process (does not require oxygen) that allows cells to produce energy by breaking down glucose when oxygen is not available.

Pigment

A substance that absorbs certain wavelengths of light and reflects others; used in photosynthesis to capture light energy.

Chlorophyll

The main green pigment in plants that absorbs light energy for photosynthesis, especially blue and red wavelengths.

Thylakoid

A membrane-bound compartment inside chloroplasts where the light-dependent reactions of photosynthesis take place.

Stroma

The fluid-filled space surrounding the thylakoids in a chloroplast; where the light-independent (Calvin cycle) reactions occur.

Light-dependent Reactions

The first stage of photosynthesis that occurs in the thylakoid membranes and converts light energy into chemical energy (ATP and NADPH).

Photosystem

A protein-pigment complex in the thylakoid membrane that captures light energy and transfers electrons during the light-dependent reactions.

Light-independent Reactions (Calvin Cycle)

The second stage of photosynthesis that occurs in the stroma and uses ATP and NADPH to build glucose from carbon dioxide.

Cell Division

The process by which a parent cell divides to form two or more daughter cells, essential for growth, repair, and reproduction.

Asexual Reproduction

Reproduction involving a single organism, producing offspring that are genetically identical to the parent.

Sexual Reproduction

Reproduction involving the combination of genetic material from two parents, leading to offspring with genetic diversity.

Chromosome

A structure made of DNA and proteins that carries genetic information. In humans, there are 46 chromosomes (23 pairs).

Chromatin

A complex of DNA and proteins found in the nucleus that condenses to form chromosomes during cell division.

Cell Cycle

The series of stages through which a cell passes to divide, including interphase, mitosis, and cytokinesis.

Interphase

The phase of the cell cycle when the cell is not dividing but preparing for division, including growth, DNA replication, and preparation for mitosis.

Mitosis

The process of nuclear division that results in two genetically identical daughter cells, typically occurring in somatic cells.

Cytokinesis

The final stage of cell division in which the cytoplasm divides, creating two distinct daughter cells.

Prophase

The first stage of mitosis, where the chromatin condenses into chromosomes, and the nuclear envelope begins to break down.

Chromatid

One of two identical halves of a replicated chromosome, joined at the centromere.

Centromere

The region of a chromosome where the two chromatids are held together and where the spindle fibers attach during mitosis.

Centriole

A cylindrical structure made of microtubules that helps organize the spindle fibers during cell division in animal cells.

Metaphase

The stage of mitosis where the chromosomes align along the equator of the cell. 2nd stage

Anaphase

The stage of mitosis where the chromatids (now individual chromosomes) are pulled apart toward opposite poles of the cell. 3rd stage

Telophase

The final stage of mitosis where the chromosomes begin to de-condense, and the nuclear envelope reforms around each set of chromosomes. 4th stage

Histones

Protein molecules around which DNA wraps to form nucleosomes, helping to package and organize DNA into a compact structure called chromatin. They play a key role in gene regulation and the condensation of DNA during cell division.

nucleosome

a histone + the DNA wrapped around it.

DNA Replication

The process by which a cell makes an identical copy of its DNA before cell division. It ensures that each daughter cell receives an exact copy of the DNA. This process involves enzymes like DNA helicase (to unwind the DNA), DNA polymerase (to add new nucleotides), and ligase (to seal gaps between newly synthesized DNA strands).

RNA (Ribonucleic Acid)

RNA is a single-stranded nucleic acid molecule essential for various biological functions. It plays a pivotal role in translating genetic information from DNA into proteins, facilitating gene expression and regulation.

RNA differs from DNA in 3

ways:

RNA is single-stranded

RNA has ribose sugars, rather

than deoxyribose sugars in its

backbone.

RNA uses uracil instead of

thymine.

Messenger RNA (mRNA)

Carry copies of the DNA sequence outside of the nucleus so the message can leave the nucleus without endangering the original genetic blueprint.

Ribosomal RNA (rRNA)

Make up ribosomes

Transfer RNA (tRNA)

Carries amino acids to form protein chains

transcription

The process of making an mRNA copy from a DNA template; an enzyme called RNA polymerase unwinds a small section of the DNA strand, then uses one side of the double helix as a template to make an mRNA copy.

base-pairing rules

(Ademine=Thymine) (Citosine=Guanine)

Whenever the DNA sequence contains A, however, a uracil (U) is made rather than

a T. For mRNA

tRNA molecules

like matchmakers- they match a codon to an amino acid. These amino acids are the

building blocks of proteins.

polypeptide chain

a linear sequence of amino acids linked together by peptide bonds. These chains form the primary structure of proteins and are synthesized during the process of translation.

gene regulation.

Rather than producing unnecessary proteins, cells control which genes are used.

DNA mutations

When A nucleotide can be added, deleted, or changed.

Point mutations

caused by a mistake in base pairing for one nucleotide.