DNA Structure, Function, and Replication: Key Concepts for Biology

What does DNA stand for?

Deoxyribonucleic Acid

Who conducted the experiment that first demonstrated transformation in bacteria?

Frederick Griffith in 1928

What are the two strains of pneumonia bacteria used in Griffith's experiment?

S (smooth) and R (rough) bacteria

What characteristic does the S strain of bacteria have?

It is virulent, has a protective capsule, and appears smooth in culture.

What happens to R bacteria when mixed with S bacteria according to Griffith's conclusions?

Harmless R bacteria become virulent through a process called transformation.

What did Oswald Avery discover in 1944?

DNA was the material responsible for transformation in bacteria.

What was the key finding of the Hershey-Chase experiment?

DNA of viruses was injected into bacterial cells, confirming that DNA is the genetic material.

What are the three main roles of DNA?

Storing, copying, and transmitting genetic information.

What is the structure of DNA commonly referred to as?

A double helix.

What are the monomers of nucleic acids?

Nucleotides.

What components make up a nucleotide?

A sugar, a nitrogen base, and a phosphate group.

What are the four nitrogen bases found in DNA?

Adenine, Cytosine, Guanine, and Thymine.

Which nitrogen bases are classified as purines?

Adenine and Guanine.

Which nitrogen bases are classified as pyrimidines?

Cytosine and Thymine.

What is Chargaff's rule regarding base pairing?

The amount of adenine equals thymine, and the amount of cytosine equals guanine in DNA.

How are adenine and thymine connected in DNA?

By 2 hydrogen bonds.

How are cytosine and guanine connected in DNA?

By 3 hydrogen bonds.

What forms the backbone of the DNA ladder?

Deoxyribose sugar and phosphate groups.

What is the significance of the sequence of bases in DNA?

It encodes genetic information.

What did Erwin Chargaff discover about base proportions in DNA?

The amount of adenine always equals thymine, and cytosine always equals guanine in every organism studied.

What is the role of hydrogen bonds in DNA structure?

They connect the nitrogen bases together, forming the rungs of the DNA ladder.

What is the function of the protective capsule in S strain bacteria?

It allows the bacteria to be virulent and cause disease.

What occurs if DNA is destroyed in Avery's experiment?

Transformation to new bacteria does not occur.

What is the significance of the Hershey-Chase experiment in the context of DNA?

It provided strong evidence that DNA is the genetic material, not protein.

What is the shape of DNA described as?

A twisted ladder or double helix.

Who discovered the base pairing rules?

Erwin Chargaff

What did Rosalind Franklin and Maurice Wilkins use to study DNA structure?

X-ray diffraction

What shape did Watson and Crick propose for DNA?

A double helix

What holds the nitrogen bases together in DNA?

Hydrogen bonds

What are the nitrogen base pairs in DNA?

Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G)

What is the backbone of DNA made of?

Sugar and phosphate groups

True or False: The sequence of bases on one strand of DNA determines the sequence on the other strand.

True

What three components make up a nucleotide?

A nitrogenous base, a sugar, and a phosphate group

What is the process called when DNA duplicates itself?

DNA replication

What model of DNA replication was supported by Meselson and Stahl?

The semiconservative model

What enzyme unwinds the DNA during replication?

DNA helicase

What are the proteins that keep DNA strands apart during replication called?

Single-stranded binding proteins

What enzyme adds RNA primers to the DNA strands?

RNA primase

What enzyme adds new nucleotides to the growing DNA strand?

DNA polymerase

What are the small fragments of DNA on the lagging strand called?

Okazaki fragments

What enzyme connects Okazaki fragments?

DNA ligase

What are the ends of eukaryotic chromosomes called?

Telomeres

What is the origin of replication?

The point where DNA replication is initiated

What is a replication fork?

The area where DNA starts to unzip during replication

How long would DNA replication take if there was only one replication fork?

33 days

How quickly can DNA be replicated in human chromosomes with multiple replication forks?

About 8 hours

How does DNA replication differ in prokaryotes compared to eukaryotes?

Prokaryotes typically start replication from a single point, while eukaryotes can begin in multiple places.

What happens to a chromosome each time it replicates?

It gets a little shorter due to the loss of telomere DNA.

What is the significance of DNA sequence similarity between species?

The closer the DNA code is between species, the more closely related they are.

Organisms obtain energy from food when the _ within food molecules are broken.

Chemical bonds

Which type of organisms must consume food to obtain energy?

Heterotrophs

What is the amount of energy required to raise the temperature of 1 gram of water by 1C?

A calorie

How many calories are contained in one dietary Calorie (kilocalorie)?

1000 calories

Cells use the energy released from food to produce which high-energy compound?

ATP (Adenosine triphosphate)

What term describes metabolic reactions that synthesize larger molecules and usually require energy?

Anabolic reactions

Reactions that require an input of energy are classified as _.

Endergonic

What term describes metabolic reactions that break down substances and release energy?

Catabolic reactions

Reactions that result in a net release of energy are classified as _.

Exergonic

Which process is an example of a catabolic reaction where glucose is broken down in the presence of oxygen?

Cellular respiration

How do warm-blooded animals utilize the energy from cellular respiration besides for movement and repair?

Heat production

Which three components make up an adenosine triphosphate (ATP) molecule?

Adenine, ribose, and three phosphate groups

In the relationship between energy processes, photosynthesis is said to "deposit" energy while cellular respiration "_" energy.

Withdraws

List the three main stages of cellular respiration in chronological order.

Glycolysis, Krebs Cycle, and Electron Transport Chain

What are the folds of the inner mitochondrial membrane called?

Cristae

What is the name of the innermost compartment of the mitochondria?

The matrix

What does the term "glycolysis" literally mean?

Sugar breaking

In which part of the cell does glycolysis occur?

The cytoplasm

How many ATP molecules are required as an initial investment to start glycolysis?

2 ATP

What is the net gain of ATP molecules produced during glycolysis?

2 ATP

Glycolysis breaks one molecule of glucose into two molecules of _.

Pyruvate (Pyruvic acid)

Which electron carrier is produced when $NAD^{+}$ accepts high-energy electrons during glycolysis?

NADH

Why is glycolysis classified as an anaerobic process?

It does not require oxygen to function.

Before the Krebs cycle begins, pyruvate is rearranged into which two-carbon molecule?

Acetyl-CoA

During the conversion of pyruvate to Acetyl-CoA, which gas is released as a byproduct?

CO2 (Carbon dioxide)

In which specific location of the mitochondria does the Krebs cycle take place?

The mitochondrial matrix

Acetyl-CoA combines with a four-carbon compound (oxaloacetate) to produce which six-carbon molecule?

Citrate (Citric acid)

Per one molecule of glucose, how many total ATP are released specifically from the Krebs cycle?

2 ATP

Which two electron carriers are generated during the Krebs cycle to transport electrons to the next stage?

NADH and FADH

How many times must the Krebs cycle turn to process one molecule of glucose?

Twice

Where is the Electron Transport Chain (ETC) located in the mitochondria?

The inner membrane

What is the primary role of NADH and FADH in the Electron Transport Chain?

They pass high-energy electrons to the chain.

The energy from the Electron Transport Chain is used to pump _ from the matrix into the intermembrane space.

H+ (protons)

Which molecule serves as the final electron acceptor at the end of the Electron Transport Chain?

Oxygen O2

What byproduct is formed when oxygen accepts electrons and combines with hydrogen ions at the end of the ETC?

Water H2O

Through which protein complex do H+ ions diffuse back into the matrix to generate ATP?

ATP synthase

How many ATP molecules are produced during the Electron Transport Chain stage alone?

32 ATP

What is the overall balanced chemical equation for cellular respiration?

C6H12O6+6O2 → 6CO2+6H2O+ATP

In the presence of oxygen, what is the total number of ATP molecules produced from one molecule of glucose?

36 ATP

Approximately what percentage of the total energy in glucose is captured as ATP during cellular respiration?

36 percent

What happens to the 64 percent of energy from glucose that is not captured as ATP?

It is released as heat.

Which anaerobic process occurs to produce ATP when oxygen is absent?

Fermentation

What is the primary purpose of the fermentation step that follows glycolysis?

To regenerate NAD+ so glycolysis can continue.

What are the two most common types of fermentation?

Lactic acid fermentation and ethyl alcohol fermentation

Which organisms perform lactic acid fermentation to produce foods like yogurt and cheese?

Bacteria (such as Lactobacillus acidophilus) and some fungi

Besides carbon dioxide, what is the end product of alcoholic fermentation?

Ethyl alcohol (Ethanol)

What are the three main sources of ATP for humans during exercise?

ATP in muscles, lactic acid fermentation, and cellular respiration.

For about how many seconds can lactic acid fermentation supply enough ATP for intense activity?

90 seconds

What is the term for the extra oxygen needed after intense exercise to clear lactic acid from the body?

Oxygen debt

To which organ is lactic acid carried by the blood to be converted back into pyruvate?

The liver

For exercise lasting longer than 90 seconds, which process is required to provide a steady supply of ATP?

Cellular respiration