Bio Midterm Exam II

Smooth ER (SER)

Lipid and steroid synthesis, Detoxification, Calcium storage

Rough ER (RER)

Protein synthesis (ribosomes attached), Transport of proteins to Golgi

Key difference between RER and SER

Ribosomes present on RER, absent on SER

DNA

Deoxyribose sugar, Double strands, Bases A T C G, Located in nucleus, Stores genetic info

RNA

Ribose sugar, Single strand, Bases A U C G, Located in nucleus & cytoplasm, Protein synthesis

Simple diffusion

Transport of small non-polar molecules (O₂, CO₂)

Facilitated diffusion

Transport via protein channels, no ATP required

Active transport

Transport against gradient, requires ATP

Triglycerides

Structure: 1 glycerol + 3 fatty acids

Saturated triglycerides

No C=C bonds, Straight chains, Solid at room temp

Unsaturated triglycerides

≥1 C=C bond, Bent chains, Liquid at room temp

Osmosis

Passive movement of water molecules across a partially permeable membrane from high water concentration to low water concentration

Cohesion

Attraction between water molecules due to hydrogen bonding

Adhesion

Attraction between water and other surfaces

Polysaccharides

Large molecules made of many monosaccharides, Insoluble, Compact structure

Why polysaccharides are efficient energy storage

Many glucose units store lots of energy, Compact → fits in cells, Insoluble → does not disrupt water movement

Energy in cells

Used for active transport, biosynthesis, cell division, movement

How energy is released

During cellular respiration when glucose is broken down, Energy transferred to ATP

Enzyme

Biological catalyst that speeds up reactions

Substrate

Molecule the enzyme acts on

Fluid mosaic model

Phospholipid bilayer with embedded and mobile proteins, Dynamic and flexible

Cell recognition

Glycoproteins (sometimes glycolipids)

Amphipathic molecule

Phospholipid (Hydrophilic head + hydrophobic tails)

Active transport vs Passive transport

Active: Requires ATP, Against gradient; Passive: No ATP, Down gradient

Facilitated diffusion vs Simple diffusion

Simple: no protein; Facilitated: uses protein channels

Cellulose

Made of β-glucose, Straight chains, Structural support in plants

Photosynthesis

Occurs in chloroplasts, Converts light to chemical energy, Produces glucose and oxygen

Cellular respiration

Occurs in mitochondria, Releases energy from glucose, Produces ATP