2.1 Chemistry and cells Flashcards
Describe the generalized structure of a typical cell.
The generalized structure of a typical cell includes:
Cell membrane (Plasma membrane): Outer boundary that separates the cell’s interior from its external environment, regulating the passage of substances in and out of the cell.
Cytoplasm: Gel-like substance filling the cell’s interior, consisting of cytosol (fluid) and various organelles.
Nucleus: Control center of the cell containing genetic material (DNA) organized into chromosomes, responsible for regulating cellular activities and hereditary information.
Organelles:
Endoplasmic reticulum (ER): Network of membranes involved in protein and lipid synthesis.
Golgi apparatus: Stacked membrane-bound organelle responsible for processing, modifying, and packaging proteins and lipids for transport.
Mitochondria: Powerhouses of the cell, producing ATP through cellular respiration.
Ribosomes: Cellular structures responsible for protein synthesis.
Lysosomes: Membrane-bound vesicles containing digestive enzymes involved in breaking down cellular waste and foreign substances.
Peroxisomes: Organelles involved in detoxification and lipid metabolism.
Cytoskeleton: Network of protein filaments (microfilaments, intermediate filaments, and microtubules) providing structural support, facilitating cell movement, and aiding in cell division.
Vacuoles: Membrane-bound sacs involved in storage, digestion, and waste removal.
Cytosol: Fluid portion of the cytoplasm, containing dissolved molecules and ions necessary for cellular processes.
This generalized structure varies slightly among different cell types and organisms but serves as a fundamental framework for cellular organization and function.
describe the functions of the main organelles of a cell
Nucleus:
Contains genetic material (DNA).
Controls cellular activities and gene expression.
Mitochondria:
Powerhouses of the cell, producing ATP through cellular respiration.
Play a crucial role in energy metabolism.
Endoplasmic Reticulum (ER):
Rough ER: Site of protein synthesis and processing.
Smooth ER: Involved in lipid synthesis, detoxification, and calcium storage.
Golgi Apparatus:
Modifies, sorts, and packages proteins and lipids for transport.
Ribosomes:
Site of protein synthesis, where mRNA is translated into proteins.
Lysosomes:
Contains digestive enzymes for breaking down cellular waste and foreign substances.
Peroxisomes:
Break down fatty acids and detoxify harmful substances.
Cytoskeleton:
Provides structural support, cell shape, and movement.
Composed of microfilaments, intermediate filaments, and microtubules.
Cell Membrane:
Regulates the passage of substances in and out of the cell.
Provides structural support and cell-cell communication.
Each organelle has specific functions critical for the cell’s survival, growth, and overall functionality.
describe the composition of the cytosol
It is mainly made up of waterwithdissolved ions, gases, nutrients, water, enzymes and wastes.The cytosol is also calledintracellular cells.
describe the structure of the nucleus
The nucleus consists of:
Nuclear envelope (membrane)
Nucleoplasm (gel-like substance)
Chromatin (DNA and proteins)
Nucleolus (site of ribosome assembly)
explain the role of the nucleus in a cell
The nucleus plays a central role in the cell by:
Housing the cell’s genetic material (DNA).
Controlling gene expression and protein synthesis.
Regulating cellular activities and functions.
Facilitating cell division and inheritance of genetic information.
briefly describe the structure and funcion of the cell/plasma membrane
Structure: The cell membrane, also called the plasma membrane, is composed of a phospholipid bilayer embedded with proteins and cholesterol molecules. The phospholipid bilayer consists of hydrophilic (water-attracting) heads facing outward and hydrophobic (water-repelling) tails facing inward.
Function: The cell membrane serves as a selective barrier, regulating the passage of substances in and out of the cell. It controls the movement of ions, nutrients, and waste molecules, maintaining the cell’s internal environment (homeostasis).
Compare the plasma membrane transport processes: diffusion and osmosis.
Diffusion:
Definition: Movement of molecules from an area of higher concentration to an area of lower concentration, down the concentration gradient.
Nature: Passive process, does not require energy (ATP).
Types: Simple diffusion (direct movement through lipid bilayer) and facilitated diffusion (assisted by membrane proteins).
Example: Oxygen and carbon dioxide diffusion across cell membranes.
Osmosis:
Definition: Diffusion of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
Nature: Passive process, does not require energy (ATP).
Importance: Regulates cell volume and maintains osmotic balance.
Example: Movement of water into or out of cells based on solute concentration gradients.
Explain the mechanisms of active transport acrossthe plasma membrane giving examples.
endocytosis- a vesicle forms around the substance and moved into the cell
exocytosis- a vesicle merges with the cell membrane moving the substance out of the cells.
Sodium-potassium pump: Moves Na+ out and K+ into the cell.
Proton pump: Moves H+ ions out of the cell or into organelles.
describe the different types of matter
*solid- doesn’t channge shape and volume . eg - teeth, bone
*liquid - doesn’t change volume but takes up the shape of the container in which it is poured in . eg blood, saliva
*gas- changes the shape and volume changes to the container it is in . eg - air, oxygen
Define energy
energy is defined as the capacity to do work.
energy of 2 types- kinetic( due to motion ) and potential ( stored)
describe the components that make up atoms
atoms are made up of protons, neutrons and electrons.
Define the terms -atomic number and atomic mass
atomic number- same as the no. of protons and electrons.
atomic mass- the sum of number of protons and neutrons
describe the roleofelectrons in the formation of the three types of chemical bonds
ionic bond- the electrons are transferred between the atoms resulting in the formation of cations and anions.
covalent bond- the electrons are shared between the atoms
hydrogen bond- there is a polarity created between the hydrogen and oxygen atoms of adjacent water molecule. Formed between +ve and-ve areas of different molecule.
differentiate betweencations and anions
cations are positively charged ions formed on losing an electron.
anions are negatively charged ions formed on gaining an electron.
xplain the concept of pH and the differences between acids and bases
pH is the measurement of the hydrogen ion concentration in a solution
Acids- produces H+ ions when mixed with water.
- tastes sour
-pH less than 7
- proton donors
Base- produces OH- ions when mixed with water.
- tastes bitter
-pH more than 7
- proton acceptors
