Biology Exam 1

Hydrophilic head and hydrophobic tails

Separates intracellular and extracellular environments, anchors cytoskeleton, regulates entry/exit of substances, and facilitates cell communication

The membrane as a flexible bilayer where proteins float like icebergs in a sea of lipids

Degree of saturation, temperature, and cholesterol content

Tight junctions, anchoring junctions, and communication junctions

Restrict movement of substances between cells and prevent membrane proteins from migrating

Specialized adhesive junctions that hold cells together

Gap junctions (in animals) and plasmodesmata (in plants) allow direct exchange of molecules

Diffusion, facilitated diffusion, and osmosis

The movement of water across a selectively permeable membrane from low to high solute concentration

Water moves into the cell

Water moves out of the cell

No net movement of water

Movement of molecules against their concentration gradient using ATP

Uses ATP to move 3 Na+ out and 2 K+ into the cell

Phagocytosis, pinocytosis, receptor-mediated endocytosis

Process of vesicles fusing with the plasma membrane to release materials outside the cell

Direct contact (Juxtacrine), Paracrine, Endocrine, and Synaptic

Ligand (signaling molecule) and receptor (molecule that binds ligand)

Kinase adds a phosphate group; Phosphatase removes a phosphate group

Intracellular and cell surface/membrane receptors

Small molecules (e.g., cAMP, Ca2+) that relay signals inside the cell

Bind ligands, autophosphorylate, and activate intracellular signaling pathways

The insulin receptor

A signaling pathway that amplifies signals and regulates cell functions like differentiation and apoptosis

All organisms are made of cells, Cells are the smallest living things, Cells arise only from pre-existing cells

Diffusion efficiency decreases and the surface area-to-volume ratio decreases, making material exchange harder

Plasma membrane, cytoplasm, genetic material, and ribosomes

Bacteria and Archaea

In the nucleoid region (not enclosed by a membrane)

Peptidoglycan (Gram-positive: thick layer; Gram-negative: thin layer)

Some use flagella, which rotate to propel the cell

They can live in extreme environments and have genes similar to both bacteria and eukaryotes

Membrane-bound nucleus and organelles, more complex structures, and a cytoskeleton

Stores genetic material (DNA) in the form of chromatin

A nuclear envelope made of two phospholipid bilayers

Synthesize proteins

Free in the cytoplasm or attached to the rough endoplasmic reticulum (RER)

Endoplasmic reticulum (RER & SER), Golgi apparatus, lysosomes, peroxisomes, vesicles

Protein synthesis and processing

Lipid synthesis, calcium storage, detoxification

Modifies, packages, and distributes proteins and lipids

Breaking down macromolecules and digesting foreign material via phagocytosis

Membrane-bound structures for storage: Central vacuole (plants), contractile vacuole (protists), storage vacuoles

ATP production through oxidative metabolism

Photosynthesis in plants and some protists

Both have double membranes, their own DNA, and ribosomes

Eukaryotic organelles (mitochondria & chloroplasts) evolved from symbiotic prokaryotes

Mitochondria & chloroplasts have two membranes, their own DNA & ribosomes, and bacteria-like division process

A network of protein fibers that maintain cell shape and movement

Actin filaments, Microtubules, Intermediate filaments

Yes, but it is different from that of eukaryotes

Crawling (actin & myosin), flagella (undulate motion), cilia (wave-like motion)

9 + 2 structure: 9 pairs of microtubules surrounding 2 central microtubules

Plants & protists: Cellulose; Fungi: Chitin

A structure made of glycoproteins and collagen that supports and connects cells

Via integrin proteins embedded in the plasma membrane

It can form up to 4 covalent bonds with other atoms, allowing complex molecules

Specific molecular groups that give molecules distinct properties (e.g., hydroxyl, carboxyl)

Monomer: A single building block (e.g., amino acid, nucleotide); Polymer: A chain of monomers (e.g., protein, DNA)

The process of forming polymers by removing water

The process of breaking polymers by adding water

(CH2O)n

Energy storage (e.g., starch, glycogen) and structural support (e.g., cellulose, chitin)

Two monosaccharides linked by dehydration synthesis (e.g., sucrose, lactose, maltose)

Long chains of sugars used for storage or structure (e.g., starch, glycogen, cellulose)

DNA, RNA, and ATP

A pentose sugar, a phosphate group, and a nitrogenous base

Purines: Adenine (A), Guanine (G); Pyrimidines: Thymine (T), Cytosine (C), Uracil (U)

Uracil (U) replaces Thymine (T)

By phosphodiester bonds in a sugar-phosphate backbone

Adenosine triphosphate, the primary energy currency of the cell

Enzyme catalysis, defense, transport, support, motion, regulation, storage

Polymers of amino acids linked by peptide bonds

Central carbon, amino group, carboxyl group, hydrogen, and R group

They determine chemical properties (e.g., nonpolar, polar, charged)

Primary, Secondary, Tertiary, Quaternary

Changes in pH, temperature, or salt concentration

They are hydrophobic (insoluble in water)

Fats (triglycerides) and phospholipids

1 glycerol + 3 fatty acids

Saturated: No double bonds, solid at room temp; Unsaturated: Double bonds, liquid at room temp

They contain unsaturated fatty acids

1 glycerol + 2 fatty acids + 1 phosphate group

Polar (hydrophilic) head and nonpolar (hydrophobic) tails, forming cell membranes

The structural arrangement of cells

Living organisms have complex structures

How organisms respond to environmental changes

The processes through which organisms grow and reproduce

How organisms use energy to maintain their functions

The ability of an organism to maintain stable internal conditions

The changes in organisms over time to better fit their environment

Entities that lack cellular organization and cannot reproduce independently; they require a host cell to replicate

To understand the natural world through observation, experimentation, and reasoning

Uses specific observations to form general conclusions

Applies general principles to predict specific outcomes

A systematic process involving observation, question formulation, hypothesis testing, experimentation, data collection, analysis, and conclusion

A proposed explanation for an observation that can be tested

A mathematical statement tested using data (e.g., null and alternative hypotheses)

Assumes no effect or no difference (e.g., 'PLTL leadership does not affect MCAT scores')

Suggests an effect or a difference exists (e.g., 'PLTL leadership improves MCAT scores')

The factor being manipulated (e.g., PLTL leadership)

The factor being measured (e.g., MCAT score)

To ensure that only the independent variable is affecting the outcome

Descriptive data (e.g., color, behavior)

Numerical data (e.g., test scores, temperature)

A statistical method that models the relationship between a dependent and independent variable

By evaluating whether the null hypothesis should be rejected or not, interpreting the significance of results, and considering possible sources of error or limitations

Can only be supported or rejected based on available evidence; they cannot be proven

Presentations at conferences, peer-reviewed journal articles, and academic reports