bio midterm

Study Guide:

Exam is primarily over Chapters 5 and 6.  Students are responsible for basic information on Cellular Respiration Chapter 9, and Photosynthesis Chapter 10 as discussed in class and in the Study Guide.

Cells: The working units of Life, Chapter 5; Figure 5.6 Prokaryotic Cell, 

Figure 5.9, Eukaryotic Cells:  Animal Cell, Page 92 and Plant Cell, page 93.

Identify the organelles and structures in these cells and their function.

Energy Transformation Chapters 9 and 10

Introduction to Organelles which Transform Energy.

MITOCHONDRIA and CHLOROPLASTS, Page 98

Mitochondria: Found in Plant and Animal Eukaryotic Cells

Chloroplasts: Are found in Plant Eukaryotic cells. They the pigment Chlorophyll.  This is necessary for the capture light energy (solar energy) and the process of Photosynthesis to occur.

The Endosymbiotic Hypothesis: Some organelles formed from in-folding of the cell membrane (Endoplasmic Reticulum), and others arose by Endosymbiosis (Mitochondria, Chloroplasts and other Plastids). 

This hypothesis suggests that some organelles found in Eukaryotic Cells, where originally forms of Bacteria, which became incorporated into the cytoplasm of Eukaryotic Cells by invagination. 

Chapter: 5, Key Concept 5.5 (Illustration on Page 108.

Support for this Hypothesis

1. Size:  The size of bacteria cells and the energy transformation organelles Mitochondria and Chloroplasts are approximately the same, 1.5 microns in diameter and 2-8 microns in length (1 micron is 10-6 m ). A Eukaryotic Cell is about 100 microns in size.

1. They have the ability to reproduce and divide independently of control from the central nucleus of the Eukaryotic cell to which they belong.

1. Mitochondria and Chloroplasts have their own independent Nucleic Acids and Ribosomes. 

Cellular Respiration: Pathways that harvest Chemical Energy. Chapter 9

Mitochondria: Chapter 5, Figure 5.13

Site of Cellular Respiration.

You need to know the Cellular Respiration Equation

In the Mitochondrion, there is the breakdown of metabolites of energy-rich Glucose to eventually Adenosine Triphosphate (ATP) the universal energy currency molecule of living organisms.

Brain cells, muscle cells and other cells active in movement, growth and development require a lot of chemical bond energy to make ATP, and as a result, they tend to have large amounts of glycogen and glucose and large numbers of Mitochondria.

You need to know the structure of the Mitochondrion.

The mitochondrion has 2 membranes.

-The Outer Smooth Membrane permits substances to move in and out of the organelle.

- The Inner Membrane is characteristic of folding. The folds are structures described as CRISTAE.

-The space enclosed by the Inner membrane is called the (MITOCHONDRIAL) MATRIX. The inner membrane controls what enters and leaves the MATRIX.

-Embedded in the inner mitochondrial membrane are LARGE PROTEIN COMPLEXES which are vital and important in Cellular Respiration.

- The mitochondrial MATRIX contain RIBOSOMES, DNA and ENZYMES (Mitochondrial proteins) used for energy conversions.

Understand the terms, Metabolism and the differences between Catabolism and Anabolism

Cellular Respiration is a catabolic process (catabolism of glucose)

The 4 Important Stages of Cellular Respiration, 

-Glycolysis of Glucose to Pyruvate

-Pyruvate Oxidation

-The Kreb’s (Citric Acid) Cycle

-The Electron Transport Chain (System)

Where are the locations where these 4 processes take place?

-Glycolysis 

Takes place in the Cytoplasm: This is the conversion of Glucose, a six-carbon molecule to two three-carbon Pyruvate Molecules. This reaction requires 2 ATPs but results in 4 ATPs being formed so there is a net result of 2 ATP molecules being formed. Glycolysis does not require oxygen, so it is an anaerobic process. Also, other molecules called NADH+  are converted to NADHs (with the addition of Hydrogen)

In Anaerobic Respiration, there is no progression into aerobic processes found in the Kreb’s Cycle and The Electron Transport Chain (both which are aerobic processes).  This results in types of fermentation.  In yeast, this gives rise to Alcohol Fermentation and the production of alcohol. Sometimes when humans exercise and strain their muscles these cells are forced to operate without adequate amounts of oxygen.  This results in the cells producing Lactic Acid and this is described as Lactic Acid Fermentation.  The buildup of lactic acid in muscle cells results in Cramping.

The result of Glycolysis is:

2 ATP (net)

2 NADH

2 Pyruvate

-Pyruvate Oxidation is the conversion of Pyruvate (3 carbon) to Acetyl CoA (2 carbon) Acetyl CoA is important because it is the beginning molecule which enters the Krebs Citric acid Cycle

-The Kreb’s (Citric Acid) Cycle. 

Beginning of the Kreb’s Citric Acid Cycle is when: 

Acetyl CoA (2 C) + Oxaloacetic Acid (4 C) --- Citric Acid (6 C) A series of Oxidation Reduction reactions. 

This is located in the Matrix.  This is an aerobic series of processess.  The reactions here require oxygen. This produces 2 ATPs. In the Kreb’s Cycle, you also have NAD+ being converted to NADHs (also with the addition of Hydrogen).  Between Glycolysis and Kreb’s there are a total of 10 NADHs made from one molecule of Glucose. Similarly, there are related molecules called FADs being converted in to FADHs. Both these molecules (NADHs and FADHs) drive the processes in the Electron Transport Chain, they are electron carriers).

3 NADHs X 2 (because of Glucose) = 6 NADH

1 ATP X 2= 2 ATPs

1 FADH  X 2 = 2 FADH

-The Electron Transport Chain.  This is aerobic and this stage produces the majority of ATP (34 ATPs) Movement of protons down a proton concentration gradient to generate ATPs

The total ATPs made from one Glucose molecule is 38 ATPs

CHLOROPLASTS: Site of Photosynthesis.  Chapter 5, Figure 5.14b

A chloroplast is an example of a PLASTID.

(What is a PLASTID?)

-Plastids are not found in Animal cells.  They are found in Plants and types of Protists.

Protists 

Structure of the Chloroplast

Photosynthesis converts Light Energy into Chemical Energy, Chapter 10

Know the basic equation for Photosynthesis

The oxygen gas in the equation comes from the water (1941 Samuel Ruben & Martin Kamen-Berkley)

Photosynthesis does not occur in Eukaryotic Animal Cells because Animal Cells do not contain chloroplasts, or chlorophyll.

Photosynthesis occurs in Eukaryotic Plant Cells (Eukaryotic cells) and various forms of Algae (Eukaryotic cells) and Bacteria particularly Cyanobacteria (prokaryotic cells), which contain free floating Chlorophyll in their cytoplasm. 

Algae, which are simple single celled Eukaryotic Cells (they have organelles)

Procaryotic Cells (bacteria) do not have organelles.

Eukaryotic Cells do have organelles.

Photosynthesis in Eukaryotes

2 pathways: The Light Reactions and the Light Independent Reaction/Calvin Cycle (Dark Reaction)

 The Light Reactions take place in the Thylakoid membranes where light energy is converted to chemical energy in the form of ATP and NADPH (an electron carrier)

Sunlight is the source of energy which drives the formation of ATP from ADP and Phosphate and NADPH.

There are 2 Photosystem responsible for capturing solar energy (Photosystem II and Photosystem I).

Certain molecules form pigments.  When a special type of pigment chlorophyll absorbs a photon, the molecules are raised to an excited state and possesses more energy. Chlorophyll absorbs energy in the blue and red light wavelengths.  Light energy is passed from the pigments to the Reaction Center. The high energy electrons are then passes down energy gradients and this generates ATP and NADPH. These molecules produce energy to fuel the Light Independent Reactions.

The Light Independent Reactions / Calvin Cycle is where carbon fixation occurs.

This reaction uses ATP, NADPH (made from the light reaction) and Carbon Dioxide to make carbohydrates.  The location of the Calvin Cycle is the Stroma of the chloroplast.