Honors Bio DNA Test

Test on 3/4

What was Rosalind Franklin’s achivements?

She revealed the helical structure of DNA

What was Erwin Chargaff’s achivements?

Made the Chargaff’s Rules (A=T, C=G)

What were James Watson and Francis Crick’s achivements?

Constructed a model that showcased DNA's spiral form

What kind of macromolecule is DNA?

Nucleic Acid

What is the monomer of a Nucleic Acid?

Nucleotide

What are the three main components of a nucleotide?

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

What are the 4 nitrogen bases?

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

What are the 2 Pyrimidines?

Thymine (T) and Cytosine (C)

What are the 2 Purines?

Adenine (A) and Guanine (G)

How many strands does DNA have?

2 strands

What sugar is DNA?

Deoxyribose

What is the Sugar-Phosphate Backbone (sides of DNA) made of?

phosphate groups and deoxyribose sugars

What bonds connect the phosphate groups and the deoxyribose sugars together, forming the Sugar-Phosphate Backbone?

Covalent bonds

What are the “rungs” of DNA made of?

Nitrogen bases

What bonds connect the nitrogen bases together, creating the rungs of the DNA?

Hydrogen Bonds

What does it mean that DNA runs “anitparallel”?

One strand runs in the 5’ to 3’ direction while the other runs int he 3’ to 5’ direction, making them create a double helix

What is chromatin?

Loosely packed DNA wrapped around a protein (found when the cell is NOT dividing)

What are Chromosomes?

Tightly compacted strands of DNA (found when a cell is DIVIDING)

What are Chromatids?

one of the two identical halves of a chromosome that has been replicated in preparation for cell division.

What is a gene?

The basic unit of heredity passed from parent to child.

Where does DNA replication take place in? (Eukaryotes)

Nucleus

When does DNA replication occur?

During the “S” phase of the Cell Cycle

What is “Semi-Conservative Replication”?

Making an identical copy of a double helix using only 1 side of the DNA molecule

What is the first step of DNA replication?

Helicase “unwounds/unzips” the DNA by breaking the hydrogen bonds between each nucleotide strand

Which enzyme “unzips” the DNA by breaking the hydrogen bonds beween each nucleotide strand?

Helicase

What is the second step of DNA replication?

RNA Primase creates short RNA sequences called primers that the DNA Polymerase uses to create each DNA template strand

Which enzyme creates short RNA sequences called “primers”?

RNA Primase

Which enzyme creates new DNA template strands after binding to the RNA primers by adding a complementary base nucleotide?

DNA Polymerase

DNA Polymerase can only bind to an available _________ group

OH^-

In which direction does DNA Polymerase produce DNA in?

5’ to 3’

The strand of DNA that is created towards the “replication fork” is called the ________ ___________.

Leading Strand

The strand of DNA that is created “backwards” in short fragments is called the ______ __________.

Lagging Strand

What are Okazaki Fragments?

Short, discontinuous fragments created by DNA Polymerase in the Lagging Strand

What is the third step of DNA replication?

The short Okazaki Fragments get conneted together with a phosphate group by the enzyme called DNA Ligase.

Which enzyme connects the Okazaki Fragments with a phosphate group to complete the replication of DNA?

DNA Ligase

What are the end results of DNA replication?

2 new identical DNA strands (made up of ½ the original DNA strand and ½ of the newly synthesized strand)

Why do cells divide?

Cells divide to allow reproduction (single-celled organisms), growth and repairs, and for the production of sperm and egg cells

What are the 2 types of reproduction?

Asexual and Sexual

What is an example of asexual reproduction?

Vegetative Propagation (a cut piece of potato sprouting) and Budding (a small bud forming on the parent yeast cell and eventually splitting apart creating a new yeast cell)

What are the 2 types of cell division?

Mitosis and Meiosis

What is a Somatic Cell?

Any cell of a living organism other than a reproductive cell (goes through mitosis, has 46 chromosomes in humans)

What is a Gamete (Germ) Cell?

Sex cells/reproductive cells (the sperm and egg, has 23 chromosomes in humans)

What is the correct order of the cell cycle phases?

G₀/G₁ → S → G₂ → M

What happens in the G₁ phase?

The cell goes through rapid growth and performs its normal functions

What happens in the S phase?

The cell passes the “restriction point” of growth and begins to synthesise its DNA

What happens in the G₂ phase?

All organelles are copied and the cell goes through more rapid growth and protein synthesis. All copied DNA is checked for errors here.

What is the G₀ phase?

Cells that never move on to the S phase stay in the G₁ phase until they die, which is known as the G₀ phase.

What cells are in the G₀ phase?

Brain cells, Heart cells and Neurons (cannot be repaired b/c they don’t go through cell division)

What is the order of the phases in the M phase?

Prophase → Metaphase → Anaphase → Telophase → Cytokenisis

What phase is cell A in?

Prophase

What phase is cell B in?

Interphase

What phase is cell C in?

Anaphase

What phase is cell D in?

Telophase

What phase is cell E in?

Metaphase

In which phase does the chromosomes in the cell double during Mitosis?

Anaphase

What happens in Prophase?

• DNA condenses into chromosomes/sister chromatins

• Centrioles move towards the poles of the cell (only in animal cells)

• The nucleus/nuclear envelope disappears

What happens in Metaphase?

• Microtubles (spindle fibers) from the centrioles connect to the kinetocore of each centromere

• Chromosomes line up in the equator of the cell

What happens in Anaphase?

• Spindle fibers shorten, pulling apart the centromeres at the kinetocore

• Sister chromatins split and move towards the poles of the cell

• This temporarily doubles the number of chromosomes

What happens in Telophase?

• 2 new nuclei (nucleus) begin to form

• Chromosomes uncoil back into chromatin

• A cleavage furrow begins to form

What is the centromere?

The “center” part of 2 sister chromatids that connects the 2 together

What is the kinetocore?

The part of the centromere where the spindle fibers connect to during Mitosis

What is a diploid cell?

A cell that has “paird chromosomes” (has 46 chromosomes in humans), all somadic cells are diploid cells

What is a haploid cell?

A cell that has a “single copy” of each chromosome type (Gametes/reproductive cells, has only 23 chromosomes)

What happens during cytokenesis in animal cells?

the plasma membrane of the parent cell pinches inward along the cell's equator until two daughter cells form

What happens during cytokenesis in plant cells?

the cytoplasm is partitioned by the construction of a new cell wall, the cell plate, inside the cell

Where do the spindle fibers come from in plant cells?

Cell wall

What is cancer (definition)?

The uncontrolled growth and division of somadic cells

What determines the type of cancer you get?

Where it originates from the body (ex: started from lungs → lung cancer)

How does cancer start?

Mutations that build up during the S-Phase that never get corrected deactivate the mechanisms that control its rate of cell division

What are the mechanisms of a cell that control the rate of cell division?

• amount of nutrients/growth factors present

• Density-Dependent Inhibition

• Apotosis

What is Density-Dependent Inhibition?

Normal cells stop growing when they come in contact with another layer of cells (density)

What is Apotosis?

Pre-programmed cell death

What is Angiogenesis?

The process of cancer cells tricking the body into growing blood vessels to feed them

What are Tumors?

A mass of cancer cells

What are the 2 types of tumors?

Benign and Malignant

What is a Benign tumor?

A tumor that is NOT actively growing/spreading throughout the body

What is a Malignant tumor?

A tumor that can or is actively growin/spreading through the body

What is Metastasis?

The active spreading of cancer cells from 1 part of the body to another

What are some causes of cancer?

• Genetic Predisposition

• Country of Origin

• Environmental factors

What are Preventable Cancers?

Types of cancers in which the chance of getting it can be reduced/avoided by lifestyle changes

What are Screenable cancers?

Cancers that can be detecte and treated early on

What is the surgical treatement for cancer?

The tumors/growths are surgically removed from the body

What is radiation therapy?

The cancer cells are exposed to radiation which messes up their DNA and kills them. However, this also kills healthy cells.

What is chemotherapy?

The use of drugs/chemicals to inhibit the growth/kill cancer cells

What is Hormone Therapy?

Treating cancer by reducing the chance cancer comes back/stopping or slowing its growth by using hormones.

What is Immunotherapy?

The usage of multiple different therapies to trigger the body’s immune system to detect adn destroy cancer cells on their own

What is a telomere?

A repeating strand of DNA at the end of a chromosome that acts like an “end cap”. It keeps chromosomes in order and protets them.

What happens to the telomere in a normal cell?

It shortens as the cell divides and eventually prevents the cell from dividing further

What do telomeres have to do with cancer cells?

The telomeres in cancer cells are constantly rebuilt, which enables the cancer cells to continue divide uncontrollably

What enzyme in cancer cells rebuild telomeres?

Telomerase