Biology b: DNA and Protein Synthesis

Which is a goal of the Human Genome Project?

- Create genetic linkage map - Create physical map - Sequence all base pairs - Find disease predictors

In the study of cancer, researchers have used different types of cells, different environmental conditions, and different experimental designs. But, all researchers have arrived at the same conclusion. Which conclusion is that?

Cancer cells lack contact inhibition.

What are the three general properties of stem cells? Check all that apply.

They are capable of dividing and renewing for long periods of time. They are unspecialized cells. They can give rise to specialized cells.

Which best describes somatic mutations?

They can cause different kinds of cancer.

What is the purpose of operons in protein synthesis?

They contain promoters and operators that determine when a gene is transcribed.

Which best describes red blood cells?

They transport oxygen throughout the body.

Which cell is unspecialized?

stem cell

Human development begins with a(n)______, which is created when _______ join and the first cell division takes place.

-embryo -gametes

According to Chargaff's rule, base pairing in DNA should resemble which of the following?

A = T; C = G

A base sequence reads AAGTCG before a mutation. Which could be the base after a frameshift mutation occurs?

AGTCG

The __________________ is a source of stem cells that has the characteristics of self-renewal and limited differentiation.

Amniotic fluid

Scientists studying the same hypothesis about cancer have gotten the same result even though they have examined the hypothesis using different procedures. What could be said about the subject they are studying?

Cancer cells may behave the same regardless of their environment.

In which structure is all the genetic information of an organism found?

DNA

Describe the relationship between DNA, chromosomes, and genes.

DNA carries instructions for making the proteins a cell needs. DNA molecules are found in chromosomes. Genes are segments of DNA that contain instructions that code for proteins.

How can DNA be used to help solve a crime?

Each person's DNA is unique. Scientists use variable regions in DNA to create a DNA profile. DNA samples can be taken from blood, bone, hair, or other body tissues and products. DNA from a crime scene can be compared to DNA from a suspect. DNA typing can be used to solve old cases.

stem cells are capable of self-renewal and differentiation .

Embryonic

Who first identified DNA?

Friedrich Miescher

Explain how the discoveries by Rosalind Franklin helped Watson and Crick build an accurate model of DNA.

In 1952, Rosalind Franklin produced an image of DNA that suggested it contained two strands twisted in a double helix with a phosphate backbone and bases inside. Franklin calculated the diameter of DNA, the distance between strands and bases, the angle of the helix, and the number of bases per coil. Watson and Crick used this information to build and accurate model of DNA.

In 1953, who developed the model that is shown below? mc004-1.jpg

James Watson and Francis Crick

Based on scientific research, which statement best describes mutations?

Mutations are rare occurrences.

Which statements about mutations are true? Check all that apply.

Mutations are rare. Most forms of cancer are caused by somatic mutations.

Explain how genes are expressed for a particular trait.

One gene for a particular trait is transcribed from DNA during transcription. The code for the gene is transferred by mRNA to the ribosome for protein production to begin. Proteins are constructed from a polypeptide chain of amino acids. Once the polypeptide chain is constructed, a protein is produced and the trait can be expressed.

Answer the following questions based on the article you just read. Stem Cell Basics Why are there more debates than answers when discussing stem-cell research?

Scientists do not fully understand how stem cells proliferate and differentiate. There are ethical concerns debated when using embryonic stem cells for research. Scientists do not know the signals used by stem cells and if they are similar when forming specialized cells; they are unable to grow specialized and unspecialized cells in the lab. It is a newer technology with many questions left to answer.

Read the article. Use your understanding to answer the questions that follow. Stem Cell Basics How are stem cells currently being used in the laboratory?

Stem cells are being used to screen drugs. Scientists are using stem cells to create a model system for normal growth to determine how birth defects happen.

Label the steps for protein synthesis in order, beginning with the first step.

Step 5-Once the protein is made, the gene for a particular trait is expressed. Step 3-mRNA joins the ribosome, and the anticodons from tRNA join mRNA to form a chain of amino acids. Step 1-RNA polymerase unzips DNA and free RNA nucleotides join DNA to form mRNA. Step 4-A chain of amino acids is formed from peptide bonds, creating a protein. Step 2- mRNA is transported from the nucleus of the cell to the ribosomes of the cell.

A single strand of DNA helix has the code ATAGGC. Which would be the complementary code on the other strand of the helix?

TATCCG

Read the article and use your understanding to answer the question that follows. Tanning Beds What type of UV light is used in tanning beds, and why is it so dangerous?

Tanning beds use UVA light. The concentration of UVA rays from tanning beds is greater than from the Sun. UVA light is dangerous because it penetrates multiple layers of the skin. Some tanning beds also emit UVB light. Exposure to UV light in tanning beds can age skin and greatly increase the risk of skin cancer.

How are the order of codons determined?

The DNA sequence determines the order.

Protein Synthesis Explain the process of transcription.

The gene coding for the protein untwists and unzips. RNA nucleotides form complimentary base pairs with the DNA bases. Hydrogen bonds and sugar-phosphate bonds form and the mRNA strand is synthesized. mRNA peels off the DNA and moves to the cytoplasm.

Gene expression within the body is controlled by the cells, which determine when a specific gene should or should not be expressed. Influenza (the flu) is caused by a virus that attacks the respiratory system. Which type of gene is likely to be widely expressed in the body of someone who contracts the influenza virus?

The gene that controls production of white blood cells.

Which best describes the outcome of DNA replication?

The new DNA molecule consists of one new strand and one old strand of DNA.

What did Chargaff discover while studying bases in the DNA of organisms?

The ratios of thymine and adenine were similar, as were the ratios of guanine and cytosine.

A DNA strand has the sequence ACCGAGCTT. Which is the complementary strand of RNA?

UGGCUCGAA

stem cell:

a cell from which a new cell with a specialized function is formed

genetic code:

a set of instructions in DNA that translates genetic information from genes, in the form of a triplet codon, to amino acids, for the synthesis of proteins

Which structural characteristic is seen in RNA but not in DNA?

a single strand

stem cells are capable of self renewal and limited differentiation.

amniotic

Scientists hypothesized that E. coli contained one operon. After further experimentation, they discovered that, in fact, E. coli contained two operons. Using this information, answer the questions provided What is one way scientists are able to study operons in organisms?

by studying the number and organization of operons by reading the genome sequence

Living organisms respond to changes in environmental conditions such as temperature. Which series lists the correct order in which the body would respond to such a change?

cell, tissue, organ, organ system, organism

Rosalind Franklin is famous for which contribution to the study of DNA?

creation of an X-ray diffraction image of DNA structure

Many different types of mutations can occur within the body. Tay-Sachs disease is a deadly disorder that is caused by a missing codon in the gene coding for production of the hex A enzyme in the body. Which type of mutation is responsible for causing Tay-Sachs disease?

deletion

Which structural component is found in DNA but not in RNA?

deoxyribose

What controls differentiation?

gene expression

DNA replication allows the basic units of heredity found on segments of DNA, called ________________, to be passed on from parent to offspring.

genes

Which are segments of DNA that code for specific traits?

genes

Which discovery is attributed to Phoebus Levene?

identification of ribose and deoxyribose

The DNA sequence reads ACGTTCATT before a mutation occurs. After the mutation, the DNA sequence reads ATCGTTCATT. Which type of mutation occurred?

insertion

Which is a point mutation?

insertion

What is one benefit of mapping the human genome?

locating the chromosomal abnormalities that cause disease

What is needed for translation to occur? Check all that apply.

mRNA ribosome tRNA codons

Protein Synthesis How are amino acids assembled during translation?

mRNA attaches to the ribosome. tRNA molecules transport amino acids to the ribosome. Anti-codons and codons match up and form complementary base pairs. Peptide bonds form between adjacent amino acids to form the protein.

Explain the roles of mRNA and tRNA in protein synthesis.

mRNA is transcribed from DNA. The nucleotides in mRNA code for amino acids. tRNA translates the mRNA sequence into an amino acid sequence so proteins can be made.

Many different types of mutations can occur within the body. Sickle cell anemia is a disease that occurs when a mutation in a base pair of the hemoglobin beta gene causes a single replacement of the amino acid glutamic acid by the amino acid valine. As a result of this mutation, the individual's blood cells take on a sickle shape under certain conditions and form clusters that can block blood vessels and cause organ damage. mc017-1.jpg mc017-2.jpg Which type of mutation causes sickle cell anemia?

missense

Which type of mutation always creates a stop codon?

nonsense

DNA is a nucleic acid polymer composed of which repeating structural unit?

nucleotides

Which of the following could be a nucleotide of RNA?

ribose + phosphate group + uracil

A point mutation changes the DNA sequence CGA to CGT, but the same protein is still produced. Which point mutation occurred?

silent

stem cells are capable of self-renewal, not differentiation.

somatic cells

neurons:

specialized cells that generate and conduct electrical impulses throughout the body, allowing the body to react to stimuli and attain homeostasis

epithelial cells:

specialized cells, typically found along surfaces of organs or other structures, that transport, protect, absorb, secrete, and provide sensory signals to the body

Which type of cell is capable of self-renewal?

stem cell

Which cells are considered immortal?

stem cells

white blood cells:

the components of blood that help protect against disease-causing germs and help in blood clotting when injuries are sustained

muscle cells:

the elongated cells with the ability to contract that form the muscles of the body

differentiation:

the process of developing specialized cells from stem cells

red blood cells:

the red, disk-like components of blood that carry oxygen throughout the body

genes:

the segments of DNA that are the basic unit of heredity in organisms and are transferred from parent to offspring

codons:

the sequences of three bases that form a unit of the genetic code in DNA that determines a specific amino acid

homeostasis:

the state of maintaining a stable internal environment despite changing external conditions

genetics:

the study of heredity in organisms

Why are cells differentiated?

to perform specific functions for the body

Which is considered a chemical mutagen?

tobacco

stem cells

undifferentiated cells

When a disease-causing agent enters an organism, the immune system alerts which specialized cells?

white blood cells

A sperm cell and an egg cell fuse to form which structure?

zygote