Cell Organelles Cell parts II

Lysosomes Membrane bound organelles that contain these hydrolytic enzymes to break down materials (proteins, fats, polysaccharides, etc…). If a lot of lysosomes burst (“suicide sac”), the cell dies. Ex: Tadpole tails, and tissues between fingers of human embryos

Food digested with primary lysosomes

Mitochondria: Used to phosphorylate ADP to make ATP. Cells may have one or thousands Has two membranes The outer is smooth The inner is folded called cristae The inner has enzymes for cellular respiration

Chloroplast Chloroplast are found in specialized cells like leaves and stems. Other chromoplasts are found in petals of flowers and skins of fruits Below is a picture of plants cells with several chloroplasts

Membranes of chloroplasts A Chloroplast has 3 membranes The outer 2 are smooth The inner makes stacks of thylakoids

Inside the chloroplasts The chlorophyll and other pigments are found inside the thylakoid membrane. The pigments have the ability to covert light energy into chemical energy. A stack of thylakoids is called a granum The matrix that the granum is embedded in is the stoma. It contains enzymes for carbohydrate synthesis

Summary of chloroplast: Chloroplast contain chlorophyll and other pigments for photosynthesis. Found in certain plant cells and algae They have 3 membranes. The outer 2 are smooth and the inner one makes stacks of thylakoids. A stack of thylakoids is called a granum. Grana are embedded in the stroma which has enzymes for carbohydrate synthesis.

Below is a diagram of the thylakoid and the location of the chlorophyll

Ribosomes A workbench for protein synthesis. Has no membranes and is made of rRNA and proteins. Cells can have thousands

The Cytomembrane (Endomembrane) system Are the organelles derived from one another, or continuous with one another? Evolved from the folding in of the plasma membrane This includes the nuclear membrane, the E.R., the golgi apparatus, vesicles and lysosomes.

Diagram: Cytomembrane (Endomembrane) Theory

Endosymbiosis Hypothesis The mitochondria and chloroplast evolved from prokaryotic cells engulfing other prokaryotic cells. This is called the endosymbiosis hypothesis Evidence for Endosymbiosis Has its own circular DNA Has ribosomes Can divide on its own Synthesizes proteins Note: Flagella also thought to have come from endosymbiosis (hypothesis proposed by Lynn Margulis but never accepted)

This is called the endosymbiosis hypothesis This shows how endosymbiosis may have occurred with a prokaryotic cell taking up residence in another prokaryotic cell Mitochondria is in this diagram Chloroplast in the next diagram