Download Formation of Amino Acids

Journal 10/13/16
What do you remember about DNA? Make a list.
Objective
To learn how cells process
information
Tonight’s Homework
p 91: 1, 2, 8
p 100: 2
Bring in your active transport
device tomorrow!
Notes on Cellular Metabolism
What is metabolism?
Metabolism is the process of a cell carrying out
life functions. Growth, respiration, movement,
and everything else.
For a long time, scientists didn’t know how the
cell knew when to do each of these kinds of
things.
We now know it comes down to two things:
- Proteins
- DNA
Notes on Cellular Metabolism
Protein Synthesis
The biggest way for a cell to send out
instructions is through proteins. Proteins have
the proper shape to “plug in” to different things
in organelles, telling them what to do.
Proteins are made of
thousands of little
molecules called amino
acids. Each amino acid
twists the chain with a
new bend. After
thousands of amino
acids, you get a very specific and twisty shape.
Notes on Cellular Metabolism
There are thousands of different types of
proteins, each one serving a specific function.
So what we really want to know is… how does a
cell make proteins?
Notes on Cellular Metabolism
DNA Codes
Remember DNA? How it has 4 different kinds of
chemicals?
We can read a string of DNA like words on a
page. The order of the chemicals – the base
pairs - tells the cell what to make.
Notes on Cellular Metabolism
DNA Codes
Remember DNA? How it has 4 different kinds of
chemicals?
We can read a string of DNA like words on a
page. The order of the chemicals – the base
pairs - tells the cell what to make.
This is: G
T
C G
T C
C T
G
T
Notes on Cellular Metabolism
Each “word” is just 3 “letters” long. We call each
of these “words” a “codon”.
Most codons make either a single amino acid or
have a special code to start and stop the cell
from reading DNA.
Total, there are about 20 different amino acids.
Notes on Cellular Metabolism
Each “word” is just 3 “letters” long. We call each
of these “words” a “codon”.
Most codons make either a single amino acid or
have a special code to start and stop the cell
from reading DNA.
Total, there are about 20 different amino acids.
Examples:
AUG – Code to start reading DNA
UAA – Code to stop reading DNA
GAC – Amino acid “aspartate”
GUU – Amino acid “valine”
There is a
table in
your book
on page
103!
Notes on Cellular Metabolism
Types of RNA
So how does a cell “read”
this DNA? For that, we
have to have 3 kinds of
RNA. RNA is just like DNA,
but instead of two strands
twisting, it’s just one.
There are 3 kinds of RNA that help a cell read
DNA.
- Messenger RNA
- Transfer RNA
- Ribosomal RNA
Notes on Cellular Metabolism
Messenger RNA
This is RNA copied from the DNA in the nucleus
of the cell. This copy leaves the nucleus and
finds a ribosome so it can be read.
The ribosome then reads the mRNA and makes
the amino acid.
Notes on Cellular Metabolism
Transfer RNA
This type of RNA attaches to the end of the
mRNA and helps it “plug in” to the ribosome.
Think of this like a zipper. You can’t attach the
two ends without the thing you pull.
Just like you can’t attach mRNA to a ribosome
without tRNA.
Notes on Cellular Metabolism
Ribosomal RNA
Our ribosomes can’t read RNA without an
“instruction book”.
Ribosomal RNA is a small bit of RNA inside the
ribosome that tells it how to do this.
Notes on Cellular Metabolism
Formation of Amino Acids
Let’s look at what happens inside the ribosome
in more detail.
1) The mRNA lines up with a ribosome
Notes on Cellular Metabolism
Formation of Amino Acids
Let’s look at what happens inside the ribosome
in more detail.
1) The mRNA lines up with a ribosome
2) The ribosome looks for a “start” codon to
know where to begin.
Notes on Cellular Metabolism
Formation of Amino Acids
Let’s look at what happens inside the ribosome
in more detail.
1) The mRNA lines up with a ribosome
2) The ribosome looks for a “start” codon to
know where to begin.
3) The RNA starts going through the ribosome
one codon at a time. As it goes, the ribosome
starts putting together amino acids into a
twisty shape.
Notes on Cellular Metabolism
Formation of Amino Acids
Let’s look at what happens inside the ribosome
in more detail.
1) The mRNA lines up with a ribosome
2) The ribosome looks for a “start” codon to
know where to begin.
3) The RNA starts going through the ribosome
one codon at a time. As it goes, the ribosome
starts putting together amino acids into a
twisty shape.
4) This keeps going until the ribosome finds the
“stop” codon. Then it lets the new protein go.
Notes on Cellular Metabolism
Notes on Cellular Metabolism
Homeostasis
One last major idea here. If all the previous
stuff works properly, our cell has a good, stable
metabolism. We call this homeostasis.
Notes on Cellular Metabolism
Homeostasis
One last major idea here. If all the previous
stuff works properly, our cell has a good, stable
metabolism. We call this homeostasis.
To keep homeostasis, some organisms have to
process energy and metabolize faster. We say
they have a higher metabolic rate. Others
process slower. We say they have a lower
metabolic rate.
Notes on Cellular Metabolism
Homeostasis
One last major idea here. If all the previous
stuff works properly, our cell has a good, stable
metabolism. We call this homeostasis.
To keep homeostasis, some organisms have to
process energy and metabolize faster. We say
they have a higher metabolic rate. Others
process slower. We say they have a lower
metabolic rate.
When creatures build up material and store
energy, we call it anabolism. When they break
things down, we call it catabolism.
Exit Question
What is a codon?
a) RNA
b) A group of 3 “letters” from DNA.
c) The organelle that process RNA
d) The DNA in the middle of a cell.
e) A secret code used in World War II
f) None of the above