Biochem - Part 2 Flashcards
What are the major functions of the nucleus?
Control center of the cell, stores genetic information, regulates gene expression
The nucleus is essential for cell division and the overall functioning of the cell.
What is the role of the nucleolus?
Produces ribosomes
The nucleolus is found within the nucleus and is crucial for protein synthesis.
What do ribosomes do?
Synthesize proteins
Ribosomes can be free-floating in the cytoplasm or attached to the rough endoplasmic reticulum.
What is the function of mitochondria?
Produce ATP through cellular respiration
Mitochondria are known as the powerhouse of the cell.
What is the function of chloroplasts?
Conduct photosynthesis
Chloroplasts are found in plant cells and convert light energy into chemical energy.
What is the function of the cell membrane?
Regulates entry and exit of substances, maintains homeostasis
The cell membrane is selectively permeable.
What is the role of the cell wall?
Provides structure and protection to plant cells
The cell wall is composed of cellulose in plants.
What distinguishes smooth endoplasmic reticulum from rough endoplasmic reticulum?
Smooth has no ribosomes; rough has ribosomes on its surface
Smooth ER is involved in lipid synthesis, while rough ER is involved in protein synthesis.
What is the function of the Golgi apparatus?
Modifies, sorts, and packages proteins and lipids for secretion
The Golgi apparatus is essential for processing and shipping cellular products.
What do lysosomes do?
Digest waste materials and cellular debris
Lysosomes contain enzymes that break down biomolecules.
What is the function of vacuoles?
Store nutrients, waste products, and help maintain turgor pressure in plant cells
Vacuoles are particularly large in plant cells.
Describe a phospholipid molecule.
Composed of a hydrophilic head and two hydrophobic tails
Phospholipids are the main component of cell membranes.
How are phospholipids oriented within the cell membrane?
Hydrophilic heads face outward, hydrophobic tails face inward
This arrangement forms a bilayer structure.
What is the ‘fluid mosaic membrane model’?
Describes the cell membrane as a flexible layer of lipid molecules with embedded proteins
This model highlights the dynamic nature of cell membranes.
What is the difference between the bilayer and the fluid mosaic model?
The bilayer is a static structure, while the fluid mosaic model emphasizes mobility and diversity of components
The fluid mosaic model accounts for the movement of proteins and lipids within the membrane.
What roles do proteins play in the plasma membrane?
Transport, signaling, structural support, and enzymatic activity
Membrane proteins can be integral or peripheral.
List 5 differences between plant and animal cells.
- Plant cells have a cell wall
- Plant cells contain chloroplasts
- Plant cells have a large central vacuole
- Animal cells have lysosomes
- Animal cells have centrioles
These differences affect their functions and structures.
What do enzymes do?
Catalyze biochemical reactions by lowering activation energy
Enzymes are specific to substrates and can be affected by environmental conditions.
What is enzyme inhibition?
The process of decreasing enzyme activity through various mechanisms
Inhibition can be competitive or non-competitive.
What is allosteric regulation?
Regulation of enzyme activity through binding at a site other than the active site
Allosteric sites can enhance or inhibit enzyme function.
What is feedback inhibition?
A regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step
This prevents the overproduction of substances.
What is osmosis?
The diffusion of water across a selectively permeable membrane
Osmosis occurs from a region of lower solute concentration to higher solute concentration.
What is diffusion?
The movement of molecules from an area of higher concentration to an area of lower concentration
Diffusion continues until equilibrium is reached.
What is facilitated diffusion?
The process of transporting molecules across a membrane via protein channels or carriers
Facilitated diffusion does not require energy.
What is active transport?
The movement of molecules against their concentration gradient, requiring energy
An example is the sodium-potassium pump.
What is bulk membrane transport?
The process of transporting large quantities of substances into or out of the cell
This includes endocytosis and exocytosis.
Explain the types of transport in terms of direction of movement.
- Osmosis: water moves to balance solute concentration
- Diffusion: molecules move to lower concentration
- Facilitated diffusion: molecules move through proteins to lower concentration
- Active transport: molecules move to higher concentration
- Bulk transport: substances move in bulk
Each transport type has distinct mechanisms and energy requirements.
Explain the types of transport in terms of size of molecules.
- Osmosis: water molecules
- Diffusion: small nonpolar molecules
- Facilitated diffusion: larger or polar molecules through proteins
- Active transport: ions or larger molecules
- Bulk transport: large particles or volumes
Size influences the choice of transport mechanism.
Explain the types of transport in terms of energy requirements.
- Osmosis: no energy
- Diffusion: no energy
- Facilitated diffusion: no energy
- Active transport: requires energy
- Bulk transport: requires energy
Active and bulk transport are energy-dependent processes.
Explain the types of transport in terms of concentration gradient.
- Osmosis: moves with gradient
- Diffusion: moves with gradient
- Facilitated diffusion: moves with gradient
- Active transport: moves against gradient
- Bulk transport: can move with or against gradient
The direction of transport is key for maintaining cellular homeostasis.
