Unit 6 Lesson 3: How Cells Make Proteins Flashcards
Tsar Nicholas II and Tsarina Alexandra of Russia were delighted with the birth of their son Alexei. What did there son have
After his birth, it was soon discovered that Alexei had hemophilia.
Why was Hemophila called the royal disease
Hemophilia was once called the “royal disease” because it spread throughout the royal families of Britain, Germany, Spain, and Russia.
What does Hemophilia do
The condition prevents blood from clotting normally because it lacks certain blood-clotting proteins called fibrins.
What would happen if a person with hemophila cuts themselfs
If a person with hemophilia cuts themself, it can become a life-threatening emergency.
DNA
a nucleic acid molecule that contains genes
Every cells contains..
DNA
What is DNA used for
every cell uses the coded instructions in DNA to make proteins in the same way.
What were Alexei’s cells like
Alexei’s cells were unable to make a specific type of protein—the protein that forms blood clots because his DNA did not direct his cells to make the protein.
What are proteins
Proteins are large molecules that are composed of smaller molecules called amino acids.
What does most of the work in cells
proteins
What do proteins do
They make up the structure and are involved in the function of all the body’s tissues and organs.
What are enzymes
a type of protein that speeds up chemical reactions
What do enzymes control
As enzymes, they control all the metabolic reactions that take place in the body.
Waht does every cells contain
every cell of the body contains the codes for making the body’s proteins in its DNA.
What acts as a control center for eukaryotic cells
a nucleus is the structure that acts as a eukaryotic cell’s control center because it contains DNA.
eukarytic
of a cell type that contains membrane-bound organelles such as a nucleus
DNA is packaged into.
Within every nucleus of every cell, the DNA is packaged into threadlike structures called chromosomes.
What is a gene
a gene is a segment of a DNA molecule that contains the coded information needed to make a specific protein. One chromosome can contain thousands of genes.
Like Alexei, people with hemophilia lack the ability to make the protein they need for their blood to clot; why is that
Like Alexei, people with hemophilia lack the ability to make the protein they need for their blood to clot because the gene that codes for this protein is mutated, or changed, such that it does not code for the protein correctly.
The human body suses 20 differnt amino acids to do what
The human body uses 20 different amino acids to form all the proteins it needs.
What does protein sythesis involve
Protein synthesis involves both DNA and a different nucleic acid—RNA.
RNA is different from DNA in three ways. Elaborate
RNA contains only one strand instead of two, its backbone contains the sugar ribose instead of deoxyribose, and it has the nitrogen base uracil instead of the nitrogen base thymine. If you were to examine a molecule of RNA, you would notice that it appears to be half a DNA double strand, with the single base in each rung exposed.
There are 3 types of RNA:
messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Each type plays a unique role in protein synthesis.
What is mRNA
– a nucleic acid that carries the genetic code from DNA to a ribosome
Waht is tRNA
a type of RNA molecule that decodes the mRNA sequence into a protein
rRNA
a type of RNA, called ribosomal RNA, that is part of the ribosome
What type of moelcle is mRNA
mRNA is a messenger molecule.
What is mRNAs role
It carries the genetic code from the DNA in a chromosome to ribosomes in the cell cytoplasm. I
genetic code
a code used by all known organisms that translates mRNA codons into amino acids
ribosome
an organelle that synthesizes proteins
Where is mRNA made in eukaryotic cells and prokaroytic cells
In eukaryotic cells, DNA is in the nucleus, so mRNA is made in the nucleus. In prokaryotic cells, which lack a nucleus, mRNA is made from DNA in the cytoplasm.
Is mRNA made different depnding on the type of cells
Regardless of the type of cell, the steps for building mRNA are the same.
What is the first step in the making of mRNA
First, the hydrogen bond that holds together the two bases in each rung of DNA is broken so the two strands of the desired portion of DNA can unzip and separate. This step exposes the bases in each single strand.
What role does RNA polymerase play in the making of nRNA
An enzyme called RNA polymerase if then uses one strand from the DNA as a template to synthesize a messenger RNA molecule. The enzyme does this by bonding complementary bases to the bases in the DNA strand.
hydrogen bond
a weak bond that forms between a hydrogen on one molecule and the oxygen, nitrogen, or fluorine of another molecule
RNA polymerase
an enzyme involved in making mRNA
The process of producing an mRNA molecule from the DNA template strand is known as
transcription.
What happens once mRNA is produced
Once the mRNA molecule is produced, it moves to a ribosome in the cytoplasm of the cell, where protein molecules are formed during a process called translation.
What is translation
a process that produces a polypeptide chain from mRNA
What are ribosomes
Recall that ribosomes are small structures in which proteins are made.
What are ribosomes composed of
Ribosomes are composed of two subunits; the large subunit sits on top of the small subunit.
Ribosomes are composed of two subunits; the large subunit sits on top of the small subunit. What happens to the mRNA
The mRNA strand moves between these two units, where the information for the protein is read.
A sequence of three bases in mRNA is called a
codon.
What does each condom speficy
Each codon specifies one amino acid that will be inserted into the protein to be produced.
Where are the codons read
These codons are “read” in the ribosome, and the correct amino acids are attached in order to produce the desired protein
What determines the sequence of amino acids for the protein that iwll be made
Thus, mRNA provides the code that determines the sequence of amino acids for the protein that will be made.
What determines the order of amino acids in the protein
Since the sequence of mRNA is determined by DNA, the sequence of the bases in DNA determines the order of amino acids in the protein.
What detrmines the individual amino acids that are addes to the growwing polypeptide chain and what order they are added
The codons in mRNA determine the individual amino acids that are added to the growing polypeptide chain and in what order they are added.
polypeptide
a chain of amino acids formed during translation that will fold into a certain shape to make a protein
The codons in mRNA determine the individual amino acids that are added to the growing polypeptide chain and in what order they are added.
Why does this happen
This happens because mRNA codons base pair with tRNA molecules. These tRNA molecules are associated with a specific amino acid.
Complementary base pairing between mRNA and tRNA is the same as
base pairings in DNA but remember that uracil replaces thymine.
How many possilbe codon combinations are there
Because each codon, consists of three bases, there are 64 possible codon combinations (four possibilities for each position).
Why is the code redundant
Since there are only 20 amino acids, the code is redundant, meaning that many of these codons produce the same amino acid.
When does the polypeptide start and stop
. In addition, there are start and stop codons that direct the ribosome where to start and stop “reading” the mRNA. When the ribosome reaches a stop codon, the polypeptide chain that has been made is complete.
What other type of RNA molecule is used in translation
In translation, another type of RNA molecule, called transfer RNA (tRNA) comes into play.
What is the size of transfer molecules
Transfer molecules are small.
What at the end of the tRNA
One end contains the complementary bases to a codon on mRNA and the other end contains an attachment site for an amino acid.
Each amino acid has its own…
Each amino acid has its own unique tRNA
When does tRNA attach to a spefic amino acid
Each tRNA molecule attaches to a specific amino acid in the cell’s cytoplasm and carries it to the mRNA strand in the ribosome, where the amino acids are attached in the correct order.
The amino acids are joined togeher with what
The amino acids are joined to each other in a polypeptide chain by peptide bonds.
What does a stop condon mean at the end of mRNA
A stop codon at the end of the mRNA molecule indicates that the polypeptide is complete and translation should stop.
What happens when polypepetide chain is complete
When the polypeptide chain is complete, it detaches from the ribosome.
How does maino acid affect shape
These amino acids interact with each other in unique ways to cause the polypeptide to fold into a distinct shape depending on the sequence of amino acids. This folded polypeptide is a protein that will do a very specific function based on its shape.
What role does DNA play in forming proteins?
The sequence of bases on the molecule of DNA determines the sequence of codons on the mRNA. The sequence of codons on the mRNA determines the sequence of amino acids in the protein. Therefore, the sequence of bases determines the order of amino acids in the protein.
Why is the sequence of nitrogen bases on the mRNA molecule complementary to those on the strand of the DNA molecule that was used as a template?
The mRNA molecule is made of the same bases as the DNA molecule, except that the base uracil, instead of thymine, binds with adenine. Since adenine can only bind with its complementary base, uracil, and cytosine can only bind with guanine, the entire sequence of the mRNA molecule is complementary to the sequence in the DNA strand from which it was copied.
What are some differences between DNA and RNA?
There are three important differences between DNA and RNA. DNA has the sugar deoxyribose in its backbones, while RNA has the sugar ribose. DNA has is composed of two strands while RNA has one strand. RNA contains a nitrogen base called uracil instead of thymine.
“the structures of the proteins that carry out essential functions in specialized cells are determined by regions of DNA called genes.”
Describe the evidence and reasoning that best supports this claim.
All cells contain the sequence of DNA in a gene that determines the structure of the protein that is to be produced. The function of a protein is determined by its structure, which can be seen in the function of tissues throughout the body. Body tissues are essential for life. Therefore, genes hold the specific code that determines the structure of proteins that perform essential functions throughout the body.
Steps cells are made
- DNA zips between the base pairs.
- One of the strands of DNA directs the production of mRNA.
- The strand of mRNA moves to the cytoplasm
- A ribosome attaches tot eh mRNA
- tRNA carries amino acids to the ribsome and attaches it to the mRNa strand
- Amino acids are linked together with poptide bonds
Compare and contrast prokaryotic and eukaryotic transcription and translation.
Answer
In prokaryotes, which are cells that do not have a nucleus, both transcription and translation take place in the cytoplasm of the cell. In eukaryotes, which are cells that have a nucleus, transcription takes place in the nucleus while translation takes place in the cytoplasm.
There are 64 codons possible because each of the three positions in a codon can have one of four base choices. Would it be possible for a codon to be composed of two bases instead of three? Explain.
No. If a codon consisted of only two bases, there would be four base choices in each of the two positions. Thus, only 16 possible codons would be possible. Since there are 20 amino acids, not all of them could be carried to the ribosome for translation into a protein.
What is a mutation
a change in the sequence of bases in a gene; A mutation is any change in the DNA sequence that affects genetic information.
Wha tis hemophila caused by
hemophilia is caused by a mutation in the gene that codes for a protein that causes blood to clot.
What chromonomes do males and females inheirt form their parents
Males inherit an X chromosome from their female parent and a Y chromosome from the male parent. Females inherit an X chromosome from each parent.
For hemopila to be present what must happen
For hemophilia to be present in males, the mutation must exist on their X chromosome. On the other hand, females are affected with hemophilia only if both of their X chromosomes contain the mutation.
What do cells do
Cells are little factories that pump out proteins.
Do red blood cells ahve genes
Except for your red blood cells, which have no nuclei, all other cells in your body contain your entire set of genes.
Except for your red blood cells, which have no nuclei, all other cells in your body contain your entire set of genes. This means that every cell is capable of doing the job of another cell. But that doesn’t happen, does it?
This is due to the fact that each type of cell produces a specific set of proteins. Gene expression is regulated by enzymes called positive and negative transcription factors.
What is gene expression regulated by
Gene expression is regulated by enzymes called positive and negative transcription factors.
What does transcription factors mean
a class of proteins that regulates transcription in rukaryotes by intereacting with RNA polymerase
What does a potive or negative transcription factors mean
As their name suggests, positive transcription factors turn genes on, and negative transcription factors turn genes off.
How quickly a cell produces proteins depends on many factors. Elaborate
These factors include the number of enzymes available in the cell, the affinity of RNA polymerase and transcription factors to DNA, and how quickly destroyer enzymes dismantle the mRNA. Sometimes, foreign substances such as chemotherapy drugs can degrade proteins. If these foreign substances enter the cell, it doesn’t matter how much target protein synthesis is produced; the target protein level remains low or non-existent.
Is transcription able to start if only one of the positive transcription factors is attached to the DNA?
It depends on the gene. The first gene only required one positive transcription factor, but both positive transcription factors in Gene 2 and 3 must be on the DNA in order for mRNA polymerase to start transcription.
If scientists want to find ways to block protein synthesis, is there more than one enzyme that they can target? Explain your answer.
Yes, scientists can target any of the enzymes in protein synthesis to decrease the amount of protein that is being made. Each biomolecule is dependent on the others functioning properly to create the appropriate amount of protein.
