More Plants! Warm up 2

Compare growth due to apical and lateral meristems in dicots

Growth in plants is brought about initially with cell division at the apical and lateral meristem.

Observation of shoot/root tips with light microscope reveals regions with cell in the various stages of mitosis. (Cell division, reproduction)  

This growth process adds length to the stem or root

Secondary growth added by the Lateral meristem has two types

1.       Vascular cambium that produces secondary xylem and phloem

2.       Cork cambium produces some of the bark layer of the stem

Explain the role of Auxin in phototropism

If light is scares because an area is crowded with plants or for some other reason, a plant needs to grow towards the light so it can get as much of it as possible.

Auxins are plant hormones that cause positive phototropism of the plant shoot and seedings

Explain how water us carried by transpiration stream, including the structure if xylem vessels, traspirational pull, cohesion, adhesion and evaporation

Plants!!! Warm up

Outline the differences (5) between the monocots and dicots

Feature	Monocots	Dicots
Venation	Parallel venation	Net- like venation
Number of Cotyledons	Two	One
Floral Organs	Petals in multiples of three	Petals in multiple of 4 & 5
Roots	Fibrous adventitious	Tap root with branching laterals
Leaf Mesophyll	Spongy	Palisade and spongy
Vascular Bundle Arrangement	Arranged in rings. Divided into cortex and stele	Bundle, no particular order

Identify and describe modifications of roots, stems, and leaves of different plants. Give one example of each

Stem modification

Bulbs: Onions and lilies

·         Short vertical underground stems

·         Many fleshy highly modified leaves for the storage or nutrients

·       Can produce new plants by bulb division or development of one of the many auxiliary buds

Horizontal stems- runners

·         Spread out from the main body of the plant

·         At the point the stem touches the ground, a new root forms

·         Asexual reproduction, if a runner id broken it can establish its self as its own plant

·         Adaptation for finding water

Cacti

·         Leaves are reduced to spines to prevent water loss in transpiration

·         The stem is enlarges for storage of water

·         The stem carries out photosynthesis

Root tip modification

 Tuber/ Potato 

·         The potato is an underground modification of the root tip

·         The ‘eaten potato’ contains the carbohydrate and protein stores for the growth

·         Auxiliary buds

Tap Root modification

·         Function: Storage of water

·         Sandy soils

Some fun things about Photosynthesis

Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs.




Explain photophosphorylation in the terms of chemiosmosis.
Photophosphorylation is the production of ATP using the energy of sunlight. The process of chemiosmosis makes photophosphorylation possible. Chemiosmosis is the movement of ions across a selectively permeable membrane and down a concentration gradient. During photosynthesis, light is absorbed by cholorphyll molecules in photosystems. Electrons within these molecules are then raised to a higher energy state; they become excited. There is a high concentration of H+ from the pumping of protons. Then, H+ accumulates in the thyhlakoid space. Protons diffuse through ATP synthase where they reduce ADP to ATP.

State the final products of the two photosystems involved in the light-dependent reactions of photosynthesis.
 The final products of the two photosystems involved in light-dependent reactions of photosynthesis are ATP and NADPH.

How are the products of the light-dependent reaction important to the light-independent reaction?
The products (glucose, amino acids, organic compounds, ATP, and NADPH)of the light-dependent reaction are very important. The light-independent reactions use these products in order to fuel their processes and carry out the Calvin Cycle. It is its reactants.

Chemiosmosis in Phosphorylation

Describe chemiosmosis as it relates to oxidative phosphorylation.

Chemiosmosis involves the movement of protons (hydrogen ions) moving across a membrane (down its concentration gradient) to provide energy so that oxidative phosphorylation can occur. Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of glucose to produce ATP.

Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared to alternative fermentation processes such as anaerobic glycolysis.

The Fabulous Role of Oxygen

Role of Oxygen in Cellular Respiration

Without oxygen, cellular respiration could not occur because oxygen serves as the final electron acceptor in the electron transport system. The electron transport system would therefore not be available. It is part of the process!

Glycolysis can occur without oxygen. Although glycolysis does not require oxygen, it does require NAD+. Cells without oxygen available need to regenerate NAD+ from NADH so that in the absence of oxygen, at least some ATP can be made by glycolysis.

Role of Oxygen in Photosynthesis

Oxygen is the by-product of a water molecule breaking down to supply photosystem II with electrons in the very beginning of photosynthesis.

Enzymes Enzymes Enzymes

What is denaturation?

             

It is the process in which the folding structure of a protein is altered due to exposure to an excess of certain chemical or physical factors. This causes the protein to become inactive because it loses its properties

What does a graph for increasing substrate concentration of an enzyme look like? Describe it

It increases but begins to slow down until it reaches a plateau

Compare competitive/Noncompetitive inhibition  

Competitive inhibition is where an inhibitor is physically and structurally similar to the substrate. Because of its similarities, the inhibitor binds to the active site of the enzyme where the substrate would normally bind. This binding of the inhibitor to the enzyme means the substrate cannot bind and it must wait for its turn.

Non-competitive inhibition is when inhibitor binds to a site on the enzyme other than the active site. The binding of the inhibitor to the enzyme cause the enzyme to change shapes. This alters the active site and the substrate can no longer bind.

Discuss lock key vs. induced fit.

Induced fit is where an enzyme alters it shape to fit the substrate.

Lock and key states that an enzyme’s active site is the exact shape of the substrate, and that the substrate neatly fits in.

Both are substrate specific, just one model states that the enzyme molds to fit the substrate whereas the other says that the site is like a puzzle piece that does not change.

Don't forget about the Link reaction!

What happens during the Link Reaction you ask???

Well....

Once the pyruvate molecules form glycolysis are in the mitochondrion, enzymes in the matrix of the mitochondrion remove hydrogen and carbon dioxide from the pyruvate. This is called oxidation (removal of hydrogen or addition of oxygen) and decarboxylation (removal of carbon dioxide). Therefore, the process is called oxidative decarboxylation. The hydrogen removed is accepted by NAD+. The link reaction results in the formation of an acetyl group. This acetyl group is then accepted by CoA and forms acetyl CoA! 

Krebs is very fun

Steps of the Krebs cycle

Step 1

Acetyl CoA is combined with oxaloacetate to form a six carbon molecule of citrate.  The acetyl coenzyme A acts only as a transporter of acetic acid from one enzyme to another. Once combined, CoA is released that it may combine with another acetic acid molecule to begin the Krebs cycle again.

Step 2

Citrate undergoes an isomerization.  A hydroxyl group and a hydrogen molecule are removed from the citrate structure in the form of water.  The two carbons form a double bond until the water molecule is hadded back.  The Hydroxyl group and hydrogen molecule are in different positions so isocitrate is formed.

Step 3

Isocitrate molecule is oxidized by a NAD molecule.  The NAD molecule is reduced by the hydrogen atom and the hydroxyl group.   The NAD binds with a hydrogen atom and carries off the other hydrogen atom leaving a carbonyl group.  A molecule of CO2 is released creating alpha-ketoglutarate.

Step 4

Coenzyme A, returns to oxidize the alpha-ketoglutarate molecule.  A molecule of NAD is reduced again to form NADH and leaves with another hydrogen.  A carbon group is released as carbon dioxide and a thioester bond is formed in its place between the former alpha-ketoglutarate and coenzyme A to create a molecule of succinyl-coenzyme A complex.

Step 5

A water molecule sheds its hydrogen atoms to coenzyme A.  Then, a free-floating phosphate group displaces coenzyme A and forms a bond with the succinyl complex.  The phosphate is then transferred to a molecule of GDP to produce an energy molecule of GTP.  It leaves behind a molecule of succinate.

Step 6

Succinate is oxidized by a molecule of FAD. The FAD removes two hydrogen atoms from the succinate and forces a double bond to form between the two carbon atoms, thus creating fumarate.

Step 7

An enzyme adds water to form malate.   The malate is created by adding one hydrogen atom to a carbon atom and then adding a hydroxyl group to a carbon next to a terminal carbonyl group.

Step 8

The malate molecule is oxidized by a NAD molecule.  The carbon that carried the hydroxyl group is now converted into a carbonyl group.  The end product is oxaloacetate which can then combine with acetyl-coenzyme A and begin the Krebs cycle all over again.

Steps of Glycolysis

Steps of Glycolysis

The enzyme hexokinase adds a phosphate group to glucose producing glucose 6-phosphate. This phosphate group comes from ATP and it is converted to ADP.

The enzyme phosphoglucoisomerase converts glucose 6-phosphate into its isomer fructose 6-phosphate.

The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form a hexose-bisphosphate.

The enzyme aldolase splits the molecule into two sugars that are isomers of each other.

First the enzyme triose phosphate dehydrogenase transfers a hydrogen (H-) from the molecule NAD+ to form NADH via oxidation. Next triose phosphate dehydrogenase adds a phosphate (P) from the cytosol to the oxidized molecule. This occurs for both molecules created by lysis

The enzyme phosphoglycerokinase transfers a phosphate from the molecule to a molecule of ADP to form ATP.  The process yields two 3-phosphoglycerate molecules and two ATP molecules.

The enzyme phosphoglyceromutase relocates the P from 3-phosphoglycerate from the third carbon to the second carbon to form 2-phosphoglycerate.

The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP). This happens for each molecule of 2-phosphoglycerate.

The enzyme pyruvate kinase transfers the final phosphate from PEP to ADP to form pyruvic acid and ATP. This happens for each molecule of PEP. This reaction yields 2 molecules of pyruvic acid and 2 ATP molecules.

Warm Up #2

The structure of a Mitochondrion and its function

Cristae- Folds of the inner membrane which increase the surface area available for the electron transport chain

Inter membrane- Contains the electron transport chains and ATP synthase which create ATP by carrying out oxidative phosphorylation

Outer membrane- Separates the contents of the mitochondrion from the rest of the cell, creating the perfect environment for aerobic respiration

Space between the inner and outer membranes- Protons are pumped into this small space by the electron transport chain. Because the space is so small, a high proton concentration can be easily achieved

Matrix- Fluid inside the mitochondria which contain enzymes for the Krebs cycle and the link reaction

Ribosomes- 70s ribosomes and a naked loop of DNA are present in the matrix

Warm up #1

What is oxidative decarboxylation?

·          Biochemical that coverts pyruvate into a two carbon and CoA compound called acetyl-CoA

·         Pyruvate loses a carbon forming Co2

·         Oxidation cause electrons to be transferred from the pyruvate to NAD+ producing NADH

·         And CoA is added

What is substrate-level phosphorylation?

It occurs during glycolysis and the Krebs Cycle
It is the source for the majority of the ATP produced in aerobic respiration
It is the addition of a free phosphate to ADP to form ATP by direct donation.

What are the products of Krebs Cycle?

·         8 NADH

·         2 ATP

·         6 Co2

·         2 FADH2

What are the products of Glycolysis?

·         2 Pyruvate

·         2 Net ATP

·         2 NADH