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[DEOXYRIBONUCLEIC ACID (DNA)]
The molecule of heredity, common to all life forms, that is passed from parents to offspring
] A single, large DNA molecule wrapped around proteins. Chromosomes are located in the nuclei of most eukaryotic cells.
The building blocks of DNA. Each nucleotide consists of a sugar, a phosphate and a base. The sequence of nucleotides (As, Cs, Gs, Ts) along a DNA strand is unique to each person.
The spiral structure formed by two strands of DNA nucleotides bound together.
Fitting together; two strands of DNA are said to be complementary in that A always pairs with T, and G always pairs with C.
Where does your DNA come from?
You inherit half of your DNA (23 chromosomes) from your mother and half from your father.
This organelle is often referred to as the "control center" for the cell. Describe the role of DNA in its function
DNA is located inside the nucleus of cells where proteins needed to read and express the DNA are housed. The nucleus of the cell is called the control center, as in the commands for cell growth and function typically come from within this organelle. DNA, however, is the element that is making the actual 'commands'.
In general terms, what is the function of DNA in all living cells
The DNA in a cell is like a set of instructions. It has the information to make any protein in your body and provides the cell with instructions on how to develop and function.
What two kinds of molecules make up a chromosome?
DNA and proteins.
How are those two molecules organized structurally to form a chromosome?
Long strands of DNA are wrapped around the proteins in order to condense the DNA so it will fit inside the nucleus of the cell.
How many pairs of chromosomes are in a typical human cell
Where do each of the two chromosomes in each pair come from?
One comes from the mother and the other comes from the father.
Examine the close-up of a nucleotide shown in Infographic 7.2 and list its three components.
The three parts of a nucleotide are a phosphate, a sugar and a base.
Examine the close-up of the DNA double helix shown here and identify the nucleotides labeled "C" and "G". In which of their three components do these two nucleotides differ from one another? Is the same true of "A" and "T"?
List the name and abbreviation of each of the four nucleotides found in DNA.
Adenine (A), Thymine (T), Guanine (G) and Cytosine (C).
Which two parts of the nucleotides form the DNA backbone?
The phosphate and sugar components.
In this diagram, solid lines represent covalent bonds. Are these bonds relatively strong or relatively weak (refer to Infographic 2.3 if necessary)?
Why might it be advantageous for the backbone of each DNA strand to be held together by covalent bonds?
Covalent bonds are relatively strong and thus hold the strand of nucleotides together. If this bond were weak, the DNA would break and would likely become nonfunctional.
Which component of each nucleotide forms the "rungs" linking the two DNA strands together?
What type of chemical bond (represented by the dashed lines) holds the two strands together?
Hydrogen bonds between the bases hold the two strands together.
Are these bonds relatively strong or relatively weak compared to covalent bonds?
Hydrogen bonds are relatively weak compared to covalent bonds.
write next to each one the abbreviation of the nucleotide to which it can bond on the opposite strand to create a "rung" linking two DNA strands together:
A binds with T (in DNA) and U (in RNA)
T binds with A
G binds with C
C binds with G
If all DNA is built of the same building blocks and always forms a double helix, what feature of each individual's DNA structure is unique?
The feature of DNA that is unique for each individual is the sequence of nucleotide bases in the strands of DNA.
Which of the following best describes the location (in eukaryotic cells) and role of DNA?
DNA is located in the nucleus and contains the instructions needed to build an organism.
Which of the following best describes the chemical makeup and organization of a chromosome?
A single DNA molecule is wrapped around proteins.
Which of the following sentences best describes the number and origin of chromosomes in a typical human cell?
Each cell has 46 chromosomes (23 pairs); one in each chromosomal pair is inherited from each parent.
Which of the following best describes the structure of the DNA "backbone"?
The individual nucleotides in each DNA strand are held together by covalent bonds linking together their sugar and phosphate groups.
Which of the following best describes how the nucleotides of two DNA strands are held together to form a double helix?
The two strands are held together in the middle by hydrogen bonds linking complementary bases.
The natural process by which cells make an identical copy of a DNA molecule.
An enzyme that "reads" the sequence of a DNA strand and helps to add complementary nucleotides to form a new strand during DNA replication.
POLYMERASE CHAIN REACTION (PCR)
A laboratory technique used to replicate, and thus amplify, a specific DNA segment.
Why must cells replicate their DNA before they reproduce?
Cells must replicate their DNA before they reproduce because otherwise the only one of the resulting cells (daughter cells) after the division would contain a full genome.
List at least three examples of why cells in your body must reproduce
Cells in the body must reproduce to: repair damage, replace old and nonfunctional cells and to promote growth of the body (like the liver or bones).
List and briefly describe the two basic steps of DNA replication
1. The DNA 'unzips' by breaking the hydrogen bonds between the base pairs of the two strands. 2. DNA polymerase attaches to one strand and 'reads' the nucleotide sequence and adds complementary new nucleotides to the growing strand
During DNA replication, what does DNA polymerase do?
DNA polymerase 'reads' the DNA strand and adds on complementary nucleotides to the growing new strand.
Explain how DNA polymerase uses the rules of complementary base pairing to complete its task. Why is this important?
DNA polymerase uses the rules of complementary base pairing to pair an A with a T, and a G with a C. This complementary pairing is important because it ensures that the sequence of nucleotides in the DNA remains the same, thus coding for the same proteins.
Examine the diagram of replicated DNA strands in Infographic 7.3. How many individual DNA strands make up the original DNA molecule prior to replication? How many individual DNA strands are present after replication
There are two strands that make up the original DNA molecule prior to replication. There are 4 strands (2 DNA molecules) present after DNA replication.
Describe the composition of the two newly formed DNA double helices ("daughter molecules") with respect to the two strands in the original DNA molecule. What about their sequences?
The "daughter molecules" are made up of one original DNA strand and one newly synthesized DNA strand. Another way to say that would be to say that the daughter strands are semi-conserved. The sequences of the original DNA molecule and the newly synthesized molecules are identical.
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