Unit 6 Lesson 4: Gene Expression Flashcards
What is Gene expression
Gene expression is the process by which genetic information from a gene is used to make a protein.
What is a gene
a section of DNA that eventually translates into a protein
What would the human body without protein look like
Without proteins, your body wouldnât be able to support your muscles or major organs. In fact, your organs might not exist because they require proteins to perform their functions.
What is out outward apperance determined by
Even the outward appearance of an organism is determined by its genes.
What does the P protein control
For example, one protein, called the P protein, controls how special cells in the eye produce and store melanin, which determines eye color.
What determines the color of eyes
Brown eyes are caused by more melanin production while blue eyes have less.
What are essential for your body to function
proteins and enzymes
Where are the instructions to make protein written
and stored
he instructions to make proteins are written and stored in nucleic acids. You know these macromolecules as DNA and RNA.
What is protein synthesis
. Protein synthesis is the process during which cells make proteins.
What is the first step of orotein sythesis, what provides the code for protein
s. Recall that DNA is transcribed into mRNA in the first step of the process and that mRNA provides the code for the protein.
What happens to tRNA and codons during protein sythsis? Waht is translation
During protein synthesis, specific tRNA molecules attach to the codons in the newly formed mRNA to bring specific amino acids to the mRNA during a process called translation.
How is protein formed
In order to form a protein, amino acids within the polypeptide chain interact with one another to fold the chain into a specific shape. This shape determines the function of the protein.
How many polypeptide chains are needed for a prtoin to be made
Some proteins require multiple polypeptide chains to come together to form the final protein. Other proteins are made of a single polypeptide chain
. Some proteins also require modifications to become activated. Elaborate
These modifications can include the attachment of certain chemical groups to the amino acids or the removal of certain amino acids.
. Some proteins also require modifications to become activated. Use snakes as an example
For example, in snakes, venom is a protein, but to protect the snake, it is initially made in an inactive form. Just as it is being injected into the prey, enzymes cut off part of the venom protein, making it active.
How do you know if the protein process si finshed
If the protein will do its work in the cytoplasm, the process is finished.
What happens if the protein will be used in a partficular organelle pr shi[[ed tp the outside of the cell
If the protein will be used in a particular organelle or shipped to the outside of the cell, two cell organelles, the endoplasmic reticulum and Golgi apparatus, take care of processing and shipping the protein to its destination.
Do all cells have the same DNA
Each cell has its own purpose and expresses its proteins in different ways and at different times, yet all cells contain the same DNA.
Why do muscle cells nad brain cells have differenct functions
For example, muscle cells and brain cells have different shapes and characteristics. Muscle cells contract and brain cells transmit messages. They can have different functions because they transcribe different parts of the DNA sequence.
Does a cell make all the proteins coded in its DNA?
The answer is no. That would be a colossal waste of the cellâs energy, so proteins are made only if and when they are needed
What do proteins do
. Proteins regulate many functions in the body including contracting muscles to move bones, producing gastric juices to digest food, and producing melanin that gives your skin a dark color to protect you from ultraviolet, or UV, light.
A muscle cell has no use for melanin, so it doesnât activate that gene.
What is central dogma
A major principle of molecular biology, called the central dogma, is that genetic information flows from DNA to RNA to create functional proteins that result in the traits of an organism.
DNA nucleotide sequences code for these proteins, which are the key to gene expression.
How does a cell know when to turn a gene on or off?
Some genes are turned on, or activated, by the presence or absence of certain substances in the cell. Genes can be turned off, or repressed, by noncoding segments, segments of DNA that do not code for proteins. These noncoding segments repress gene expression by blocking the transcription of the gene.
Gene expression can change over time in response to changing environmental factors as well. An example of this is tawny owls. Elaborate
Tawny owls can be either brown or a grayish-brown color. Tawny owls live in areas that have snowy winters and the grayish-brown color helps them blend into the snow. By blending into the snow, they can be camouflaged which allows them to be better hunters. But since the overall temperature on earth is rising, the winters in the areas they live in are less snowy. Over several generations, this has caused less grayish-brown owls to be born and more brown owls to be born. The brown owls can camouflage better in the environment when there is not snow, so more brown owls then grayish-brown owls are able to survive and reproduce.
If DNA holds the code for proteins that perform various functions throughout the body, what would happen if that code was missing a base, had an extra base, or had the wrong base?
Think about how a message could be changed if a few words were misspelled or were out of place. These variations in the code can occur during DNA replication when the DNA molecule is copied. They can also occur during transcription when the DNA code is being copied into mRNA. . Bases could be inserted incorrectly or could be skipped, causing a mutation.
What is a mutation
a random change in the sequence of nucleotides in DNA or RNA/ A mutation is a change in the genetic information that can affect the production of proteins and in turn, gene expression.
How do mutations occur
Mutations can occur through natural events, environmental conditions, or even by artificial means.
What effect do mutations ahve
Many mutations have little or no effect on gene expression. However, some mutations can be harmful and can dramatically alter the way a protein functions.
What is cystic fibrosis
cystic fibrosis is an inherited disorder. It is caused by a mutation in which three bases have been deleted from the CFTR gene. The deletion of these bases results in a change in the structure of a single protein. This protein is located in the membrane surrounding every cell in the body and is needed to carry chloride ions (Clâ)
across the membrane to the cells of essential organs. Without chloride ions, water and thick mucus build up in the lungs, making breathing difficult and increasing the risk of infection. The mucus buildup also prevents the release of digestive enzymes from the pancreas into the intestines. Without digestive enzymes, the body cannot absorb essential nutrients, which could lead to malnutrition, stunted growth, and other health issues.
How can mutations be beneficial and necesary for survial
For example, many adult humans cannot digest the sugar lactose, which is present in milk and milk products. A mutation that allows a person to break down lactose to yield energy would be beneficial in populations that raise cows, sheep, and goats. This mutation could help to feed people who live in food- or nutrient-scarce areas.
What is a point mutation
Most mutations involve a change in a single base. These mutations are known as point mutations because a change occurs at a single point along the DNA sequence.
When does a point mutation occur
Typically, a point mutation occurs during DNA replication and is then passed on to a newly created cell during mitosis.
When does a subsitution mutation occur
. Substitution mutations occur when one base in a gene is replaced with another base.
What does substituion mutation affect
This mutation usually affects only one base, and thus one amino acid in the protein structure.
There are three types of substitution mutations:
silent, missense, and nonsense.
What is a silent mutation
A silent mutation is the result of a change in a base in the DNA that has no effect on the amino acid sequence in the protein.
Why does a silent mutation have no effect
Since the amino acids remain unchanged, this mutation has no effect on the protein function.
What is a missense mutation
a type of substitution mutation in which the change in the DNA sequence changes the amino acid in the protein
What is a nonsense mutation
a type of substitution mutation in which the change in the DNA sequence changes the mRNA codon to a stop codon
What does the severtiy of subsistuiton mutation depend on
The severity of substitution mutations depends on what exactly changes about the protein.
What effect do silent mutations have
no effect
What effect do missense mutations have
With missense mutations, it depends on the amino acid that is changed.
When will missense mutations ahve little affect
ome amino acids have similar chemical properties, so changes involving amino acids with similar chemical properties can have very little effect on the protein.
What is sickle cell anemia (a type of missense mutation
sickle cell anemia, which is a disease that involves a protein in red blood cells, dramatically alters how the protein functions within red blood cells and can result in the death of the individual.
What does the affect of nonsense mutations depend on
. Finally, nonsense mutations, like missense, depend on where the mutation happens.
When will a nonsense muation have the most effect
If the mutation happens near the beginning of the mRNA, then many amino acids will be affected, which could have a huge impact on the function of the protein. I
When does a nonsense mutaiton have little effecrt
If the nonsense mutation happens closer to the end of the protein, itâs possible that this may have very little effect.
Why are deletions and insertions more serious
Deletions and insertions are more serious because a large part of the DNA is affected.
what kind of mutations are deletions and insertions
frameshift mutations
What are frameshift mutation
a change in DNA that shifts the reading of the genetic message
What is the genetic code
Recall that the genetic code is read in groups of three bases, called codons in mRNA.
When does deletion occur
Deletion occurs when one base is removed, and it affects the remainder of the amino acid sequence in the protein.
what is deletion
a type of mutation that involves one or more bases being deleted from the DNA sequence
Use a sentence that demonstarates deletion
Consider the sentence: The cat ate the rat. Image that you must read this sentence three letters at a time. If the c is deleted, the sentence will be read as: The ata tet her at. Notice how everything past the mutation is affected because of how the reading frame was shifted. The sentence becomes meaningless.
What affect does insertion ahve
Insertion also affects a large portion of the amino acid sequence of a protein because it adds an additional base to the DNA sequence.
What is insertion
a type of mutation that involves one or more bases being added to the DNA sequence
Use a sentence that describes insertion
Think of the sentence: The cat ate the rat. Insert the letter t, and the sentence will be read as: The cat tat eth era t. You can see how a gene would be greatly affected by a deletion or insertion, especially if these mutations occur near the beginning of the protein.
when do chromosomal mutations occur
Chromosomal mutations occur when the structure of a chromosome is altered. Pieces of chromosomes are sometimes lost or duplicated during cell division.
What are the types of chromosomal mutations
For example, part of the chromosome may be lost, resulting in loss of one or more genes. Part of a chromosome may be repeated, resulting in a duplication of one or more genes. Or a segment of a chromosome may be lost from one chromosome and inserted into another chromosome, a mutation called a translocation. Finally, part of the chromosome can be inverted such that the order of the genes is reversed.
What is inversion chromosomal
Broken chromosome parts joins it again but it is turned 180 degree
What is translocation in chromsomes mutations
Non-homologous chromosomes exchange segements
Protein synthesis is the process of making proteins using the instructions embedded in DNA. Based on what youâve learned in this narrative, what are the steps of protein synthesis?
- DNA us transcribed into mRNA
- mRNA is translated into amino acids
- Amino acids form a chain
- THe amino acid chain is folded into protein in the endoplascmic reticulm
In protein synthesis, DNA is first transcribed into mRNA. This mRNA is then translated into amino acids. The amino acids form a chain and this chain is folded into the protein in the endoplasmic reticulum.
All cells make all the proteins encoded in their genome all at once.
Is the statement true or false?
false; each type of cell makes a specfic set of proteins
Explain how the nucleotide sequence of your DNA determines your eye color?
Nucleotide sequences code for proteins. If your DNA code results in a low amount of melanin in your eye, you will have blue eyes. If it results in a higher amount of melanin to be produced, you will have brown eyes.
Based on what youâve learned about gene expression, research and explain the role of a digestive enzyme that is produced only when you start eating food.
Any digestive enzyme produced by the stomach or pancreas is correct. Students should discuss what macromolecule their particular enzyme digests. For example, pepsin produced by the stomach digests proteins.
Why is it important that some genes are expressed at times and not expressed at other times?
Many genes do not need to be expressed all the time because the proteins they code for are not needed. Gene expression is only activated when the protein is needed. This conserves energy and resources in a cell.
â Based on what youâve learned so far about the relationship between DNA and protein, speculate on what introns and exons are.
Introns are noncoding sections in DNA. Exons contain the codes for proteins.
what happens to the protein if a change occurs before the start or after the stop signal?
No change happens to the protein because the sections before the start signal and after the stop signal do not code for protein.
Can you think of a way for scientists to test the relationship between a gene and a protein?
Inactivate the gene and see if the protein is still being made by the cell.
How can scientists test the relationship between a protein and a trait? How can the scientist be sure that the relationship is causal and not just a correlation?
Student answers should discuss disabling a certain protein and observing any changes in the organismâs traits. To make sure that the change is causal and not correlation, the student should discuss instances where a trait is altered but the protein in question has not been disabled.
Genetic variation can change for many reasons. One of them is climate change elaborte
Climate change is caused by the increased amount of carbon dioxide in the atmosphere from people driving vehicles, operating factories, and using electricity. This has caused the overall temperature on earth to increase. This increase in temperature is causing many organisms in a species to die, changing which genes are passed on and which are n
What were tawny owls like
Since tawny owls live in places that get a lot of snow, it is more beneficial for them to have a lighter, grayish-brown coat color. This helps them camouflage against the snow and be less visible to other animals.
Tawny owls can also be a deeper brown color. This helps them camouflage against brown tree trunks when it is not snowy.
What are tawny owls like now
In less snowy conditions, owls with a brown coat that can camouflage against tree bark will have a better chance of surviving.
This means that the grayish-brown tawny owls will be the ones who die. So, the brown coat trait will be passed down more than the grayish-brown coat trait. Therefore, more owls will be brown than grayish brown.
Genes are turned into proteins. What do proteins determine?
The traits of an organism.
What is an impact of climate change?
Rising temperatures
What are two coat colors of the tawny owl?
Brown and grayish-brown
Why does the coat color of tawny owls matter?
It helps them camouflage and hide from other animals.
