Chapter 12 Flashcards by Victoria Rivas

Were actually two different varieties, of the same bacterial species

Strains

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British scientist. Was trying to figure out how bacteria makes people sick. Had isolated two very similar types of bacteria from mice

Frederick Griffith

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Grew into smooth colonies on culture plates, the disease-causing bacteria

S Strain

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Produced colonies with rough edges, harmless bacteria

R Strain

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Griffith injected mice with the disease causing bacteria. What happened to the mice

Developed pneumonia and died

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Griffith injected the mice with the harmless bacteria. What happened to the mice

Stayed healthy

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To figure out if the s-strain bacteria produced toxin that made the mice get sick what did he do?

He took a culture of the s-strain, heard the cells to kill them

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Injected the heat-killed bacteria into the mice. What happened?

They survived, suggesting that the cause of pneumonia was not a toxin from disease-causing bacteria

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Mixed the heat-killed, s-strain bacteria with live, harmless bacteria from the r-strain, what happened

The mice developed pneumonia and died. When he examined the lungs he found them to be filled with the disease-causing bacteria

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One type of bacteria has been changed permanently into another

Transformation

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Wanted to determine which molecule from the heat-killed bacteria was most important for transformation. Extracted a mixture of various molecules from the heat-killed bacteria. Carefully treated the mixture with enzymes that destroyed proteins, lipids, carbohydrates and RNA. transformation still occurred. Tried it with DNA and it worked

Oswald Avery

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Was the transforming factor

DNA

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Avery and his team discovered that

DNA stores and transmits genetic information from one generation of bacteria to the next

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Studied a bacteriophage that was composed of DNA and proteins want to determine which part of the virus entered the bacterial coat, grew viruses in culture containing radioactive isotopes of phosphorus and sulfur. Mixed the marked viruses with bacterial cells. Then separate the viruses from the bacteria and tested the bacteria for radioactivity. Concluded that the genetic material of the bacteriophage was DNA, not protein

Alfred Hershey and Martha Chase

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True/False: Hershey and Chase confirmed Avery’s results, convincing many scientists that DNA was the genetic material found in genes-not just in viruses and bacteria, but in all living cells

True

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Tiny, nonliving particles that can infect living cells

Viruses

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A kind of virus that infects bacteria. Enters a bacterium, attaches to the surface of bacterial cell and injects its genetic information

Bacteriophage

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Acts to procure many new bacteriophages

Viral Genes

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DNA that makes up genes must be capable of doing what to the genetic information in a cell?

Storing, copying and transmitting

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Genes for blood type and eye color have to do even more. Genes control patterns of development

Storing Information

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Before a cell divides, it must make a complete copy of every one of its gene

Copying Information

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DNA molecules must be carefully sorted and passed along during cell division. Careful sorting is especially important during the formation of reproductive cell in meiosis

Transmitting

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Is a nucleic acid made up of nucleotides joined into long strands or chains by covalent bonds

DNA

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Are long, slight acidic molecules originally identified in a cell nuclei. Are made up of smaller subunits, linked together to form long chains

Nucleic Acid

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Are the building blocks of Nucleic acid

Nucleotides

Nucleotides are made up of three basic components

5-carbon sugar called deoxyribose, phosphate group, nitrogenous base

Are bases that contain nitrogen

Nitrogenous base

DNA has four kinds of nitrogenous base

Adenine (A), Guanine (G), Cytosine (C), Thymine (T)

The nucleotides in a strand of DNA are joined by covalent bonds from between

Sugar and phosphate

Austrian-American biochemist. Discovered that the percentage of (A) and (T) are almost equal in any sample of DNA. same thing applies to (c) and (G)

Erwin Chargaff's

(A)=(T) and (G)=(C)

The Chargaff's a Rule

Used a technique called x-Ray diffraction to get information about the structure of DNA. Purified a large amount of DNA, then stretched the DNA fibers in a thin glass tube so that most of the strands were parallel. The x-Ray pattern does not reveal the structure of DNA, but it shows that the strands in DNA are helix

Rosalind Franklin

Twisted shaped like coils of a spring

Helix

Built a three dimensional model of DNA that was made of cardboard and wire. It explained the specific structure and properties of DNA. discovered that hydrogen bonds could form between certain nitrogenous base, providing just enough force to hold the two strands together

James Watson and Francis Crick

Two strands of twist around each other like spiral staircases. Explains Chargaff's rule of base pairing and how the two strands of DNA are held together

Double Helix

Two strands of DNA running in opposite directions

Antiparallel

The perfect fit between A-T and G-C nucleotides. Explains how DNA can be copied or replicated, because each base on one strand pairs with one-and only one-base on the opposite strand

Base pairing

Before the cell divides, it duplicates its DNA in a copying process. Occurs during the later interphase of the cell cycle, insures that each resulting cell has the same complete set of DNA molecules. DNA molecules separate into two strands and then produce tow new complementary strands

Replication

TACGTT produces a strand with the complementary base sequence

ATGCAA=2 DNA molecules

Is an enzyme that joins individual nucleotides to produce a new strand of DNA. "Proofreads" each new DNA strand, so that each molecule is a near-perfect copy of the original

DNA Polymerase

DNA at the tips. It is difficult to replicate

Telomeres

Cell use this to solve the problem by adding short, repeated DNA sequences to the telomeres. Helps prevent genes from being damaged or lost during replication. It is often switched off in adults cells. In cancer cells, may be activated, enabling cells to grow and proliferate rapidly

Telomerase

Have a single, circular DNA molecule in the cytoplasm, containing nearly all the cells genetic information

Prokaryotes Cells

Have up to 1000 times more DNA. Nearly all of the DNA is found in the nucleus

Eukaryotic Cell

Consists of DNA, tightly packed together with proteins to form a substance called chromatin

Eukaryotic chromosome

Are proteins around which chromatin is tightly coiled

Histones

Does not start until regulatory proteins bind to a single starting point on the chromosome. The protein then triggers the beginning of the s phase, and the DNA replication beings. The cell starts from a single point and proceeds in two directions until the entire chromosome is copied. The two chromosome produced by replication are attached to different points inside the cell membrane and are separated when the cell splits to form two new cells

Prokaryotic DNA replication

Begins at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is completely copied. Damaged regions of DNA are sometimes replicated,resulting in changed to DNA base sequence that may alter certain genes and produce serious consequence

eukaryotic DNA replication

On the top rail the strand is said to be oriented from

5 to 3

The strand at the bottom runs in the opposite direction and is oriented from

3 to 5

DNA coils around histones to form

Nucleosomes

Coil to form chromatin fibers

Nucleosomes

Separate.Serves as templates and produce DNA molecules that have one strand of parental DNA and one strand of new DNA

Parental Strands of DNA

An enzyme, is responsible for unwinding and unzipping the double helix

Helicase

Reads and connects the original DNA (nucleotides)

DNA polymerase

Elongated as the DNA unwinds

Leading strand

Elongates away from the replication fork

Lagging strand

The lagging strand is synthesized discontinuously into small segments called

Okazaki Fragments

Links the two sections

DNA ligase

Y shaped region on a replicating DNA molecule where new strands are growing.

Replication fork

short segment of RNA used to initiate synthesis of a new strand of DNA during replication

RNA primer

enzyme that creates and lays down RNA primer

Primase

a protein ring that slides along DNA and holds the polymerase in place during replication

Sliding clamp

RNA is a single strand to DNA's double helix RNA's ribose has one more oxygen than deoxyribose RNA contains uracil instead of thymine

What are the differences between DNA and RNA?

What are the three parts of DNA replication and when does it all happen?

DNA replication happens the S phase of Interphase and is split into the binding of enzymes to existing DNA, unwinding of the double helix, and synthesis of new matching strand for each existing strand

What was learned from Griffith's experiment

Dead bacteria somehow transmits a genetic material to live bacteria.

What are the three main parts of DNA replication?

1. The binding of enzymes to 3 main parts 2. Unwinding of double helix 3. Synthesis of new matching strand for each existing

The area where replication begins

Replication point

Adenine pairs with what to have how many hydrogen bonds?

thymine with 2 H bonds

Cytosine pairs with what to have how many hydrogen bonds?

guanine with 3 H bonds

Removes the RNA primase

RNase H

Prevents reannealing

SSB