dna replication
each time a new cell is made, the cell must receive an exact copy of the parent cell dna. the new cells then receive the instructions and information needed to function. the process of copying dna is called replication. replication occurs in a unique way - instead of copying a complete new strand of dna, the process \saves\ or conserves one of the original strand. for this reason, replication is called semi - conservative. when the dna is ready to copy, the molecule \unzips\ itself and new nucleotides are added to each side.
the image showing replication is similar to the dna and mrna coloring. note the nucleotides are shown as 2 parts - the sugar and phosphate (color blue) and one of the four bases identified by shape, color the same as you did on the other model.
the blueprint of life
every cell in your body has the same \blueprint\ or the same dna. like the blueprints of a house tell the builders how to construct a house, the dna \blueprint\ tells the cell how to build the organism. yet, how can a heart be so different from a brain if all the cells contain the same instructions? although much work remains in genetics, it has become apparent that a cell has the ability to turn off most genes and only work with the genes necessary to do a job.
to build the body, the code carried on messenger rna travels to the ribosomes where three bases within the code (called a codon) specify a single amino acid. a long mrna chain could contain thousands of these amino acids. when linked together, the amino acids form proteins, which make up many structures in the body.
in this section, color the bases and rna chain the same as you did previously.
color the amino acids red.
1. why is the nucleus called the \control center\ of the cell?
2. what is a gene?
3. where in the cell are chromosomes located?
4. dna can be found in what organelles?
5. what two scientists established the structure of dna?
6. replication is called \semi - conservative\ because half of the original strand is
7. what are the sides of the dna ladder made of?
8. what three parts make up a single nucleotide
9. what are the 4 bases that make up the rungs of the dna ladder?
10. what sugar is found in dna? in rna?
11. how do the bases bond together? a bonds with g bonds with
12. why is rna necessary to act as a messenger?
13. proteins are made where in the cell?
14. how is rna different from dna? (list 3 things)
15. the process of copying dna is called
16. what is the shape of dna?
17. proteins are made from what subunits?
18. what base is found in mrna, but not dna?
19. how do some cells become brain cells and others become skin cells, when the dna in all the cells is exactly the same. in other words, if the instructions are exactly the same, how does one cell become a brain cell and another a skin cell?
20. why is dna called the \blueprint of life\?

Question

Accepted Answer

### Question 1: Why is the nucleus called the "control center" of the cell?
# Brief Explanations:
The nucleus contains the cell's DNA, which holds the genetic instructions (blueprint) for cell functions, growth, and reproduction. These instructions regulate all cellular activities, so the nucleus controls the cell's operations.
# Answer:
Because it contains the cell's DNA, which holds the genetic instructions that regulate all cellular activities (such as growth, function, and reproduction).

### Question 2: What is a gene?
# Brief Explanations:
A gene is a segment of DNA that contains the specific instructions (code) to make a functional product, usually a protein or an RNA molecule. Genes determine traits and control cellular processes by encoding the information needed for these products.
# Answer:
A gene is a segment of DNA that contains the instructions (code) to make a functional product (e.g., a protein or RNA molecule), and it determines traits/controls cellular processes.

### Question 3: Where in the cell are chromosomes located?
# Brief Explanations:
Chromosomes, which carry DNA, are located within the nucleus of eukaryotic cells. The nucleus is the organelle that houses the cell's genetic material in a condensed form as chromosomes.
# Answer:
Chromosomes are located in the nucleus of the cell (in eukaryotic cells).

### Question 4: DNA can be found in what organelles?
# Brief Explanations:
In eukaryotic cells, DNA is primarily in the nucleus. Additionally, mitochondria (and chloroplasts in plant cells) have their own DNA, as they are thought to have evolved from prokaryotic organisms and retain genetic material for their functions (like energy production).
# Answer:
DNA is found in the nucleus, mitochondria (and chloroplasts in plant cells).

### Question 5: What two scientists established the structure of DNA?
# Brief Explanations:
James Watson and Francis Crick, using data from Rosalind Franklin (X - ray crystallography of DNA) and others, proposed the double - helix structure of DNA in 1953, establishing our modern understanding of DNA's structure.
# Answer:
James Watson and Francis Crick.

### Question 6: Replication is called "semi - conservative" because half of the original strand is ______
# Brief Explanations:
In DNA replication, the double helix unwinds, and each original (parent) strand serves as a template for a new (daughter) strand. After replication, each new DNA molecule consists of one original (conserved) strand and one newly synthesized strand. So half of the original strand is conserved (or saved) in the new DNA molecule.
# Answer:
conserved (or saved, or retained in the new DNA molecule)

### Question 7: What are the sides of the DNA ladder made of?
# Brief Explanations:
The "sides" of the DNA double - helix (ladder) are made of alternating sugar (deoxyribose) and phosphate groups. These form the backbone of the DNA molecule, with the sugar - phosphate units linked by covalent bonds.
# Answer:
The sides of the DNA ladder are made of alternating deoxyribose (sugar) and phosphate groups.

### Question 8: What three parts make up a single nucleotide?
# Brief Explanations:
A nucleotide, the building block of DNA and RNA, consists of three components: a sugar (deoxyribose in DNA, ribose in RNA), a phosphate group, and one of the nitrogen - containing bases (adenine, thymine, cytosine, guanine in DNA; adenine, uracil, cytosine, guanine in RNA).
# Answer:
A single nucleotide is made of a sugar (deoxyribose/ribose), a phosphate group, and a nitrogen - containing base (A, T/U, C, G).

### Question 9: What are the 4 bases that make up the rungs of the DNA ladder?
# Brief Explanations:
The "rungs" of the DNA double - helix are formed by the base pairs. The four nitrogen - containing bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair with each other (A - T, G - C) to form the rungs.
# Answer:
The four bases are adenine (A), thymine (T), cytosine (C), and guanine (G).

### Question 10: What sugar is found in DNA? ______ In RNA? ______
# Brief Explanations:
DNA (deoxyribonucleic acid) contains the sugar deoxyribose, which has one less oxygen atom on the sugar ring compared to ribose. RNA (ribonucleic acid) contains the sugar ribose.
# Answer:
In DNA: deoxyribose; In RNA: ribose

### Question 11: How do the bases bond together? A bonds with ______ G bonds with ______
# Brief Explanations:
In DNA, the bases follow specific base - pairing rules. Adenine (A) forms hydrogen bonds with thymine (T), and guanine (G) forms hydrogen bonds with cytosine (C). This complementary base - pairing is crucial for DNA replication and transcription.
# Answer:
A bonds with T (thymine); G bonds with C (cytosine)

### Question 12: Why is RNA necessary to act as a messenger?
# Brief Explanations:
DNA is located in the nucleus and is too large to leave it. RNA (specifically mRNA) is single - stranded and can carry the genetic code (from DNA) out of the nucleus to the ribosomes (in the cytoplasm), where proteins are synthesized. So it acts as a messenger to transfer genetic information from DNA to the site of protein production.
# Answer:
Because DNA is in the nucleus and cannot leave, while RNA (mRNA) can carry the genetic code from DNA in the nucleus to the ribosomes (in the cytoplasm) to direct protein synthesis.

### Question 13: Proteins are made where in the cell?
# Brief Explanations:
Proteins are synthesized at the ribosomes. Ribosomes can be free in the cytoplasm or attached to the rough endoplasmic reticulum. They read the mRNA (carrying the genetic code) and assemble amino acids into proteins based on that code.
# Answer:
Proteins are made at the ribosomes (either free in the cytoplasm or attached to the rough endoplasmic reticulum).

### Question 14: How is RNA different from DNA? (list 3 things)
# Brief Explanations:
1. Sugar: RNA has ribose, DNA has deoxyribose. 2. Strands: RNA is usually single - stranded, DNA is double - stranded (double helix). 3. Bases: RNA has uracil (U) instead of thymine (T), while DNA has thymine (T) and adenine (A), cytosine (C), guanine (G).
# Answer:
1. Sugar: RNA has ribose, DNA has deoxyribose. 2. Structure: RNA is single - stranded, DNA is double - stranded. 3. Bases: RNA has uracil (U), DNA has thymine (T).

### Question 15: The process of copying DNA is called ______
# Brief Explanations:
The process by which a cell makes an exact copy of its DNA is known as DNA replication. During replication, the double helix unwinds, and each strand serves as a template for a new complementary strand.
# Answer:
replication (DNA replication)

### Question 16: What is the shape of DNA?
# Brief Explanations:
DNA has a double - helix shape, which can be visualized as a twisted ladder. The two strands of DNA (made of sugar - phosphate backbones) are coiled around each other, with the base pairs forming the rungs of the ladder.
# Answer:
The shape of DNA is a double helix (twisted ladder - like structure).

### Question 17: Proteins are made from what subunits?
# Brief Explanations:
Proteins are polymers made up of smaller units called amino acids. There are 20 different amino acids that can be linked together in different sequences to form a wide variety of proteins, with the sequence determined by the genetic code in DNA.
# Answer:
Proteins are made from amino acids (as their subunits).

### Question 18: What base is found in mRNA, but not DNA?
# Brief Explanations:
In mRNA (and other types of RNA), the base uracil (U) is present. In DNA, the base thymine (T) is present instead of uracil. So uracil is the base found in mRNA but not in DNA.
# Answer:
Uracil (U)

### Question 19: How do some cells become brain cells and others become skin cells, when the DNA in ALL the cells is exactly the same? In other words, if the instructions are exactly the same, how does one cell become a brain cell and another a skin cell?
# Brief Explanations:
All cells have the same DNA, but different cells "turn on" (express) only the genes necessary for their specific function and "turn off" the others. This process is called gene regulation or cell differentiation. For example, brain cells express genes related to neural function, while skin cells express genes related to skin structure and function.
# Answer:
Through cell differentiation (gene regulation): cells turn on (express) only the genes needed for their specific function (e.g., brain - related genes in brain cells, skin - related genes in skin cells) and turn off the others, even though all cells have the same DNA.

### Question 20: Why is DNA called the "Blueprint of Life"?
# Brief Explanations:
DNA contains the genetic instructions (code) that determine the structure, function, growth, and reproduction of all living organisms. Just like a blueprint for a building specifies how to construct it, DNA specifies how to build and maintain an organism, including the production of proteins and regulation of cellular processes.
# Answer:
Because DNA contains the genetic instructions (code) that determine an organism's structure, function, growth, and reproduction (like a blueprint specifies how to build a structure).

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QUESTION IMAGE

Question

Explanation:

Question 1: Why is the nucleus called the "control center" of the cell?

Answer:

Question 2: What is a gene?