Cellular organelles

Cell

The simplest collection of matter that can live, forming the basic unit of structure and organization in organisms.

Robert Hooke

Scientist who first observed cells in cork using a simple compound microscope in 1665.

Antonie van Leeuwenhoek

A master microscope maker who discovered bacteria and protozoa, known as one of the fathers of microbiology.

Cell Theory

A fundamental concept in biology stating that all living organisms are composed of cells, the cell is the basic unit of life, and cells arise from pre-existing cells.

Prokaryotic Cell

A type of cell that is unicellular, less organized, and lacks a membrane-bound nucleus.

Eukaryotic Cell

A type of cell that is multicellular, more organized, and contains internal membranes that compartmentalize functions.

Plasma Membrane

A boundary that separates the living cell from its non-living surroundings, exhibiting selective permeability. Allows nutrients in and allows waste out.

Cytoplasm

the entire region between the cell membrane and the nucleus that houses DNA (cytosol + organelles)

Membrane Structure

Asymmetric phospholipid bilayer. Lipids are scattered between these phospholipid molecules (determine fluidity). Proteins are embedded and otherwise attached. Carbohydrates exist on the outer surface.

Saturated fatty acids

make membranes less fluid

Unsaturated fatty acids

make membranes more fluid

Phospholipid

Amphipathic lipid molecules. Head and Tail conneted by glycerol.

Phospholipid Head

Polar End. Consists of phosphoric acid conjugated to a base (Choline, Serine etc)

Phospholipid Tail

Non-Polar End. Consists of tails of long hydrocarbon chains - fatty acids

Phospholipid Bilayer

The fundamental structure of biological membranes, consisting of two layers of phospholipids with hydrophobic tails facing inwards and drophilic heads facing outwards.

four major phospholipids

phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol

Organelle

An intracellular compartment that carries out a specific function within the cell.

2 types of organelles

Membraneous organelles and Non-membraneous organelles

Membraneous organelles

 nucleus

 rough endoplasmic reticulum

 smooth endoplasmic reticulum

 mitochondria

 Golgi apparatus

 lysosomes

 peroxisomes

Non-membraneous organelles

 ribosomes

 cytoskeletal structures

 condensed protein structures

Nucleus

The organelle that stores genetic information (DNA) and is involved in gene expression.

Nuclear membrane

Definition: A double-lipid bilayer structure that encases the nucleus in eukaryotic cells. It contains pores for selective transport

Nuclear Lamina: maintains the shape and integrity of the nucleus.

Chromosomes

dynamic assemblies of DNA and proteins, i.e. chromatin

Ribosome

A cellular structure that synthesizes proteins according to the information in genes.

Endoplasmic Reticulum

An interconnected network of membrane-enclosed sacs involved in the synthesis and export of lipids and proteins, consisting of rough (rER) and smooth (sER) types.

Golgi Apparatus

The "post-office" of the cell, responsible for sorting, packaging, and modifying macromolecules.

Mitochondria

Organelles known as the power plants of the cell, generating ATP through aerobic respiration.

Mitochondria function

power plants of all eukaryotic cells

generate energy for the cell

combine oxygen with food molecules to produce ATP (aerobic respiration)

calcium storage

regulation of programmed cell death (apoptosis)

Lysosomes

The cell's waste disposal system, containing digestive enzymes that function optimally at low pH.

3 pathways leading to lysosomes

– phagocytosis

– endocytosis

– autophagy

Peroxisomes

Organelles involved in recycling and detoxification, containing oxidative enzymes and self-replicating capabilities.

histones

the major proteins of chromatin

Nucleosome

the basic structural unit of chromatin

Nucleolus

A structure within the nucleus responsible for ribosomal RNA (rRNA) gene transcription and early ribosome assembly.

Membrane Proteins

Proteins associated with the plasma membrane, classified as integral (penetrating the membrane) or peripheral (not embedded).

Cholesterol

A steroid molecule that stabilizes membrane fluidity, reducing movement at high temperatures and hindering solidification at low temperatures.

Integral proteins

penetrate the hydrophobic core, many are “transmembrane”

Peripheral proteins

are not embedded in the membrane at all, they are often bound to exposed integral proteins or loosely to the surface of the