Search This Blog

Science ki duniya

Plant Hormones

Get link
Facebook
X
Pinterest
Email
Other Apps

May 02, 2023

Plant hormones also known as plant

growth factors are chemical substances

that accelerate inhibit or otherwise

affect growth.

indole-3 acetic acid IAA

the most common form of auxin and how we discovered what auxins do.

At the apex of the stem the auxin IAA is produced.

Under unilateral light (shining on one

side) IAA

is redistributed to the shaded side,

creating a gradient of the hormone

across the stem. IAA travels between

cells by diffusion.

IAA activates proton pumps, which

lowers the pH . This activates enzymes

(expansins) to break bonds in the cell

wall. The loosening of the cell wall

allows water to enter the cell and

turgor pressure increases.

Cells on the shaded side become

elongated and cause the shoot tips to

bend towards the light.

Darwin investigated using oat

coleoptiles .He found that there is no

bending response to light when the

coleoptile tip is removed.

It means that the tip must be

stimulated by light. To investigate

further, Darwin cover the tip to prevent

light from reaching it.

The lack of bending response confirmed

that the tip must be stimulated.

When the light was shone on the tip, the

lower regions were covered the

coleoptile did bend.

It mean that only the tip needs to

be stimulated.

Peter Boysen-Jensen a thin flake

of the mineral mica which blocks

chemical movement.

When it was inserted in the illuminated

side, bending occurred normally.

But when the mica was inserted in the

shaded side there was no bending, showing

that the message to bend travels down

the shaded side.

Because the mica doesn't block

electrical signals, this also suggested

that the message was chemical.

Arpad Paal's experiment, replacing a

segment of the tip of center, increased

understanding of how the hormone is

distributed.

Even in the dark the coleoptile bent

towards the side without a tip.

Frits Went removed the coleoptile

tip and then incubated it on a block of agar.

The agar was then placed on the

coleoptile, off-center, in darkness.

Hormone that the agar had absorbed

traveled down the side of the shoot,

causing a response. The amount of bending

is proportional to the amount of hormone

in the agar. huh

Winslow Briggs inserted a very thin

glass plate vertically through the tip.

The glass does not prevent light

transmission, but there was no bending.

Auxin cannot travel through glass and

it's concentrations remain equal on

either side.

When the glass plate was inserted below

the tip, auxin moved across to establish

a hormone gradient

when the tip was examined ,70% of auxin

was found on the shaded side.

Thank you

Get link
Facebook
X
Pinterest
Email
Other Apps

Comments

Gram Staining

May 20, 2023

Gram Staining Y ou will learn how to perform gram staining this technique utilizes a four step standing procedure with two different dyes and is one of the first tests used when trying to identify unknown species of bacteria using a wax pencil label a microscope slide with your initials then draw a circle about one centimeter in diameter on the slide using a metal inoculation loop sterilize it by flaming using aseptic technique at a drop of sterile water so that a film appears across the loop transfer the water into the circle drawn by the wax pencil flame the metal loop again to sterilize after allowing it to cool use the metal lube to transfer a colony of bacteria growing on an auger plate make sure to lightly touch the bacterial colony to avoid transferring too many bacteria when finished flame the loop to sterilize you let the liquid completely evaporate leaving behind a dry spot on the slide this will take at least 10 minutes on...

Separation of Photosynthetic Pigments by Chromatography

April 30, 2023

How you can separate leaf pigments by a process known as chromatography? In this example I'm going to use spinach leaves so the first step is for you to obtain your plant that contains the pigments you wish to separate break up one of the leaves and de little pieces and place it in a mortar add a few drops of acetone and a little bit of sand as this helps with grinding up the leaves use the pestle mortar to grind up the leaves and to release the pigments if it helps here you can add a few more drops of acetone but ultimately the objective is to obtain a concentrated pigment in a liquid at the bottom of the mortar. Chromatography Paper after you've done this then you need to prepare your chromatography paper now this does actually work best with thin layer chromatography paper but you can also use regular chromatography paper to prepare you're going to obtain a pencil and it is important that it's a pencil not a pen because a pen contains other pigments use the pencil ...

Plant DNA extraction - CTAB Method

April 15, 2023

Plant DNA extraction - CTAB Method An extraction of DNA from plant samples using c tab method 100 ml of setup lysis purple can be prepared using this description after collection of plant samples i have to measure 200 milligram and grind it with liquid nitrogen then transfer all ground plant samples into an append of tube and add 700 microliters of sit up lysis buffer vortex the mixture then incubate at 65 degrees Celsius for 20 minutes in a water bath after incubation centrifuge samples at 10 000 rpm for 10 minutes after centrifuge transfer supernatant to a clean tube and add an equal volume of chloroform and isoamyl alcohol after addition of chloroform and iso-mine alcohol mix it well using vortex and centrifuge at 10 000 rpm for 10 minutes after centrifuge you will see an aqueous upper layer and an organic bottom layer now transfer the aqueous layer to a clean tube while transferring the quest layer...