TEAS Life Science

What are the levels of biological organization in order from simplest to most complex?

- Atom, Molecule, Organelle, Cell, Tissue, Organ, Organ System, Organism, Population, Community, Ecosystem, Biosphere

What are the three principles of cell theory?

1. All living things are made of cells

2. The cell is the basic unit of life

3. All cells come from pre-existing cells

What is the defining feature of prokaryotic cells?

- They have NO membrane-bound nucleus and NO membrane-bound organelles — DNA floats freely

What is the defining feature of eukaryotic cells?

- They have a membrane-bound nucleus and membrane-bound organelles

What organisms are prokaryotes?

- Bacteria and Archaea

What organisms are eukaryotes?

- Animals, plants, fungi, and protists

What do prokaryotes and eukaryotes have in common? -

Both have genetic material, cytoplasm, ribosomes, and a cell membrane

What is the cell membrane?

- A selectively permeable barrier that controls what enters and exits the cell — found in ALL cells

What is selective permeability?

- The ability of the cell membrane to allow only specific materials in and out

What is the cytoplasm?

- The jellylike fluid inside the cell that surrounds and supports all internal structures — found in all cells

What is the cytoskeleton?

- A network of fibers that provides structural support and helps with cellular movement — found in eukaryotic cells

What are ribosomes and what do they do?

- Small organelles that synthesize proteins — found in ALL cells including prokaryotes

Where can ribosomes be found in a cell?

- Floating freely in the cytoplasm or attached to the rough endoplasmic reticulum

What is the nucleus?

- The control center of eukaryotic cells that houses and stores DNA — found only in eukaryotes

What is the nucleolus?

- A specialized area inside the nucleus where ribosomes are assembled

What is the rough endoplasmic reticulum?

- An organelle studded with ribosomes that synthesizes and transports proteins

What is the smooth endoplasmic reticulum?

- An organelle without ribosomes that synthesizes lipids and performs detoxification

What is the Golgi apparatus?

- The packaging and distribution hub of the cell — modifies, sorts, and ships proteins to their destinations

What are mitochondria?

- The powerhouse of the cell — produces ATP energy through cellular respiration using glucose and oxygen

What are chloroplasts?

- Organelles found only in plant cells that perform photosynthesis — converting light energy into glucose

What are lysosomes?

- Membrane-bound organelles filled with enzymes that digest waste, cellular debris, and invasive organisms — found mainly in animal cells

What are vacuoles?

- Storage organelles — large in plant cells where they maintain pressure and aid growth, small in animal cells

What is the cell wall?

- A rigid outer layer that provides support and protection — found in plants, fungi, and bacteria but NOT animal cells

What is the cell wall of plant cells made of?

- Cellulose

What is the cell wall of fungi made of?

- Chitin

What are centrioles?

- Organelles that help organize cell division — found in animal cells only

What organelle is the post office of the cell?

- Golgi apparatus — it packages and ships proteins

What organelle is the powerhouse of the cell?

- Mitochondria

What organelle is the garbage truck of the cell?

- Lysosome — digests waste and worn out materials

What is the phospholipid bilayer?

- Two layers of phospholipids that make up the cell membrane — hydrophilic heads face outward, hydrophobic tails face inward

What does hydrophilic mean?

- Water loving — the phosphate heads of the cell membrane face outward toward water

What does hydrophobic mean?

- Water fearing — the fatty acid tails of the cell membrane face inward away from water

What is passive transport?

- Movement of substances across the cell membrane without energy, from high to low concentration

What is diffusion?

- Passive movement of molecules from an area of high concentration to low concentration until equal

What is osmosis?

- The passive movement of water specifically across a semipermeable membrane from high to low concentration

What is facilitated diffusion?

- Passive transport that uses protein channels to help substances cross the membrane — no energy required

What is active transport?

- Movement of substances from low to high concentration — requires energy in the form of ATP

What is endocytosis?

- The process where a cell engulfs large substances by wrapping its membrane around them — taking material IN

What is exocytosis?

- The process where a cell releases substances by fusing a vesicle with the membrane — pushing material OUT

What is phagocytosis?

- A type of endocytosis where the cell engulfs solid particles — white blood cells do this to destroy pathogens

What is pinocytosis?

- A type of endocytosis where the cell takes in liquid

What happens to a cell in a hypotonic solution?

- The solution has less solute than the cell — water moves INTO the cell — cell swells and may burst

What happens to a cell in a hypertonic solution?

- The solution has more solute than the cell — water moves OUT of the cell — cell shrinks

What happens to a cell in an isotonic solution?

- Equal solute concentration inside and outside — no net movement of water — cell stays the same size

What are the four macromolecules?

- Carbohydrates, Lipids, Proteins, Nucleic Acids

What is the monomer of carbohydrates?

- Monosaccharides — simple sugars like glucose

What are the functions of carbohydrates?

- Quick energy, structural support in cell walls

Give examples of carbohydrates

- Glucose, starch, glycogen, cellulose, chitin

What is the monomer of proteins?

- Amino acids

What are the functions of proteins?

- Structure, enzymes, transport, immune function, hormones, cell membrane channels

Give examples of proteins

- Enzymes, hemoglobin, antibodies, insulin, collagen, muscle fibers

What are lipids made of?

- Fatty acids and glycerol — but lipids have no true monomer

What are the functions of lipids?

- Long-term energy storage, cell membrane structure, hormones, insulation

Give examples of lipids -

Fats, oils, waxes, cholesterol, phospholipids, steroids

What is the monomer of nucleic acids?

- Nucleotides

What are the functions of nucleic acids?

- Store and transmit genetic information, direct protein synthesis

Give examples of nucleic acids

- DNA and RNA

What macromolecule makes up enzymes?

- Proteins

What macromolecule makes up the cell membrane?

- Lipids — specifically phospholipids

What macromolecule provides quick energy?

- Carbohydrates

What macromolecule provides long-term energy storage?

- Lipids — specifically triglycerides

What is anabolism?

- Building small molecules into larger ones — requires energy — example: building proteins from amino acids

What is catabolism?

- Breaking large molecules into smaller ones — releases energy — example: breaking down amino acids into urea and CO2

What is metabolism?

- The combination of both anabolism and catabolism — all the chemical reactions in the body

Does anabolism require or release energy?

- Requires energy — you are building something which takes effort

Does catabolism require or release energy?

- Releases energy — you are breaking something down which releases stored energy

What are enzymes and what do they do?

- Proteins that speed up or accelerate chemical reactions in the body — they are biological catalysts

What is enzyme denaturation?

- When an enzyme loses its 3D shape and stops functioning — caused by extreme pH or high temperature

What pH and temperature conditions cause denaturation?

- pH that is too high or too low, and temperatures that are too high

Does low temperature denature enzymes?

- No — low temperature slows the enzyme down but preserves its 3D shape

What happens to an enzyme at its optimal pH and temperature?

- It works at maximum efficiency — its 3D shape is intact

Why does enzyme shape matter?

- The 3D shape of the enzyme is essential for it to bind to its substrate and catalyze a reaction — denaturation destroys this shape

What is the structure of DNA?

- A double helix made of two strands of nucleotides — like a twisted ladder

What are the three parts of a DNA nucleotide?

- A deoxyribose sugar, a phosphate group, and a nitrogenous base

What are the four nitrogenous bases in DNA?

- Adenine, Thymine, Cytosine, Guanine — A T C G

What are the base pairing rules for DNA?

- A pairs with T — G pairs with C — always

Memory trick for DNA base pairing?

- Apples in the Tree — Adenine pairs with Thymine. Cars in the Garage — Cytosine pairs with Guanine

What is the sugar in a DNA nucleotide?

- Deoxyribose

What is the sugar in an RNA nucleotide?

- Ribose

How many chromosomes do humans have?

- 46 chromosomes — 23 pairs — one set from each parent

How many chromosomes are in human sex cells?

- 23 — half the normal amount

What is a gene?

- A specific segment of DNA that codes for a protein — located on a chromosome

What is chromatin?

- DNA wrapped around histone proteins to help organize and store genetic material in the nucleus

What are histones?

- Proteins that DNA wraps around to form chromatin — helps keep DNA neatly organized

What is gene regulation?

- The process of activating and deactivating specific genes — not every gene is active in every cell at all times

What are the three types of RNA?

- mRNA — messenger RNA, tRNA — transfer RNA, rRNA — ribosomal RNA

What does mRNA do?

- Carries the genetic instructions from DNA in the nucleus out to the ribosome

What does tRNA do?

- Carries specific amino acids to the ribosome during translation

What does rRNA do?

- Makes up part of the ribosome itself

How is RNA different from DNA?

- RNA is single stranded, uses ribose sugar, contains uracil instead of thymine, and can leave the nucleus

What base does RNA use instead of thymine?

- Uracil — U

What are the base pairing rules for RNA?

- A pairs with U — G pairs with C

Memory trick for RNA base pairing?

- Apple Under the Tree — Adenine pairs with Uracil. Cars in the Garage stays the same — Cytosine pairs with Guanine

What is transcription?

- The process of copying DNA into mRNA — happens in the nucleus

What enzyme carries out transcription?

- RNA polymerase

What is translation?

- The process of reading mRNA to assemble a protein — happens at the ribosome in the cytoplasm

What is a codon?

- A group of three mRNA bases that codes for a specific amino acid

What is an anticodon?

- The three-base sequence on tRNA that is complementary to the mRNA codon

What is the start codon?

- AUG — signals the ribosome to begin building the protein

What are stop codons?

- UAA, UAG, UGA — signal the ribosome to stop building the protein and release it