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Cells and Genes Final
Final Exam
84
Biology
Undergraduate 2
12/11/2009

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Cards

Term
What are the 5 stages of the cell cycle, and what occurs in each stage?
Definition

1. 1st gap phase: G1, growth and preparation for DNA synthesis

2. Synthesis: S phase, cell synthesizes a replica of the genome

3. 2nd Gap phase: G2, 2nd growth phase prepares the cell for mitosis. During this phase mitochondira and other organelles replicates, microtubules begin to assemble at a spindle

4. M Phase, Mitosis, replicated chromosomes are partitioned. 

5. C phase, Cytokinesis, the cytoplasm divides, creating two daughter cells. 

 

 

Term
How long does the cell cycle take?
Definition

The length of the cell cycle varies.

Cells in animal embryos can complete their cell cycle in under 20 min. 

Mature cells (for example skin cells) divide in about 24 hours. 

Liver cells have cell cycles lasting more than a year. 

Most of variation in the length of the cell cycle between one organism or cell type and another occurs in the g1 phase. 

Term
What is a chromosome?
Definition

It is tightly coiled DNA.

The vehicle by which hereditary information is physically transmitted from one generation to the next; in a bacterium the chromosome consists of a single naked circle of DNA; in eukaryotes, each chromosome consists of a single linear DNA molecule and associated proteins.  

Term
What is interphase?
Definition

G1, S, and G2 constitute interphase. 

Interphase is the portion of the cell cycle between cell divisions. 

Chromosomes are not visible during interphase. 

DNA Replication occurs during interphase

Term
What occurs in prophase of mitosis? 
Definition

Nuclear envelope disappears

Chromosomes are tightly coiled, condensed, and visible

Chromosomes appear as two sister chromatids held together at the centromere

Cytoskelton is disassembled: spindle begins to form

Golgi and ER are dispersed

 

 

 

Term
What occurs in metaphase of mitosis?
Definition

Chromosomes line up alone "metaphase plate"

Spindles made of tublin microtubules attach to centromere such that the kinetochores of sister chromatids are attached to microtubules from opposite poles

Chromosomes attach to microtubules at the kinetochores 

Term
What occurs during anaphase of mitosis?
Definition

Motor proteins (i.e. kinesin) walks along microtubule pulling chromosomes apart.  

Depolymerization (like pacman munching along) happens at centromeres 

Spindle poles move apart

Term
What are viruses?
Definition

- They are "genetic entities"

-They are bits of information in the form of DNA and/or RNA

 

Term
What happens during telophase of mitosis?
Definition

Chromosomes are clustered at opposite poles and decondense

Nuclear envelopes reform around chromosomes

Golgi Complex and ER reform

Term
True or False: Viruses can replicate and transcribe independently of a host cell
Definition
false
Term
What happens during cytokinesis? And how does this phase differ in animals and plants?
Definition

In animal cells, cleavage furrow (belt of actin) forms to divide the cells.

In plant cells, cell plate forms to divide the cells. 

Term
True or false: A virus can sometimes replicate out of synchrony by making a protein coat and evading the immune system
Definition
True
Term
What are viruses defined by
Definition
an absence of color and bacteria
Term
How is meiosis different than mitosis?
Definition
Meiosis is combination of sperm (1n) and egg (1n).  There is no replication. It consists of two rounds of division called meiosis 1 and meiosis 2. During prophase 1 synaptonemal complex forms between homologues. Crossing over occurs. 
Term
What is the function of the protein coat that surrounds the virus?
Definition
It protects the virus and allows it to travel and not die in the air and travel from person to person
Term
Dyers Hypothesis- Where do viruses come from?
Definition
Ex. family tree, animals and humans are all branches. For instance humans and pigs could be on branches next to each other. The virus's are the twigs on our branches that are the viruses that belong to that species. Sometimes neighboring branches form new virus's. For instance swine flu infected us from the neighboring pig branch. (viruses can act more independently than one would think)
Term
What happens during prophase 1 of meiosis?
Definition

-Chromosomes begin to condense

-Spindle of microtubules begins to form

-The DNA has been replicated. 

-There are homologous chromosomes, they pair up and become closely associated during synapsis. 

-Crossing over occurs, forming chiasmata, which hold homologous chromosomes together. 

Term
What happens during Metaphase 1 of meiosis?
Definition

-Pairs of homologous chromosomes align along the metaphase plate. Microtubules from opposite poles attach to sister kinetochores of each homologue. 

-A kinetochore microtubule from one pole of the cell attaches to one homologue on a chromosomes, while a kinetochore microtubule form the other cell pole attaches to the other homologue pair. 

Term
What happens during Anaphase 1 of meiosis?
Definition

-Kinetochore microtubules shorten

-Homologue pairs are pulled apart.

-One duplicated homologue goes to one pole of the cell, and the other goes to the other pole. 

-Sister chromatids do not separate. (CONTRAST to MITOSIS)

 

Term
What happens in telophase I of meiosis?
Definition

-Separated homologues form a cluster at each pole of the cell, and the nuclear envelope reforms around each daughter cell nucleus. 

-Cytokinesis may occur. 

-Resulting 2 cells have 1/2 the number of chromosomes as the original cell. 

-There are two nonidentical sister chromatids that form the homologous chromosomes. 

Term
What happens in prophase II or meiosis? 
Definition
A new spindle apparatus forms in each cell, and the nuclear envelope breaks down. 
Term
What happens between telophase I and prophase II of meiosis?
Definition
Typically a brief interphase, with no S phase. 
Term
What happens in Metaphase II of meiosis?
Definition

-A completed spindle apparatus is in place in each cell. 

-Chromosomes consisting of sister chromatids joined at the centromere align along the metaphase plates in each cell. 

-Kinetochore microtubules from opposite poles attach to kinetochores of sister chromatids. 

Term
What happens in Anaphase II of Meiosis?
Definition
-Microtubules shorten=> the centromeres split, and sister chromatids are pulled to opposite poles of the cells. 
Term
What happens during Telophase II of Meiosis?
Definition

-The nuclear membranes reform around four different clusters of chromosomes.

-After cytokinesis, four haploid cells result. 

 

Term
After meiosis why are no two cells alike?
Definition
-No two cells are alike due to the random alignment of homologous pairs at metaphase I and crossing over during prophase I. 
Term
What does Professor Dyer mean when she says there is a rhythm to mitosis?
Definition
She said there is a specific rhythm to mitosis and when that rhythm is thrown off there are huge consequences. 
Term
Virus spectrum, left end
Definition

-potential for loss or not gained at all, is out of synchrony with our cells

-sometimes doesnt replicate or wont even make it to into DNA

-Most viruses are on this end of the spectrum

Term
Virus spectrum, middle
Definition

-Virus in synchrony with cells, is either benign or beneficial 

-Virus has the potential to go towards either side of the spectrum

-replicates at the same time as the DNA

Term
What is nondisjunction and when does it occur?
Definition
Failure of chromosomes to move to opposite poles during either meiotic division. It produces one gamete that lacks a chromosome and one that has two copies. 
Term
Virus spectrum, right end
Definition

-Out of synchrony, does not wait for DNA to replicate

-has small number of genes, throws them together in a messy way

-builds protein coat, has an extra disguise coat around it 

-travels via sneezing coughing itching etc (could be caused by the virus in order for it to travel)

Term
What are aneuploid gametes? What typically happens when gametes are aneuploid?
Definition

They are gametes with an improper number of chromosomes. 

In humans, this condition is the most common cause of spontaneous abortion. 

Term
What is a virus? 
Definition
Any of a group of complex biochemical entities consisting of genetic material wrapped in protein; viruses can reproduce only within living host cells and are thus not considered organisms. 
Term
What is an REO virus?
Definition

-means respiratory entoric orphan virus

-orphan means that the virus is not connected to a disease

-they are found in placentas and some think they may even be beneficial

Term
What makes a bacterium pathogenic?
Definition
Its parasitic relation with other organisms
Term
How does a virus enter a cell?
Definition

- It fuses onto the the cell and then the cell creates a bud to let it in

-It can enter because of the disguise coat that is around the virus

 

Term
What is a broken virus
Definition
A virus that can't make a protein coat or bud off cells to replicate
Term
What is a helper virus
Definition

A virus that bands to another virus to replicate

Two helper viruses can join to be a successful virus

Term
Viruses can be:
Definition

-Single or double stranded DNA

-Single or double stranded RNA

-Combination of DNA and RNA

 

Term
What can happen if there are problems during crossover/recombination?
Definition
nondisjunction or uneven crossovers
Term
What are the consequences of uneven crossovers during meiosis?
Definition
Chromosomes size and shape can be different. 
Term
What problems can arise from nondisjunction?
Definition

 nondisjunction of autosomes- failure to survive development, down syndrome, edwards syndrome, 

nondisjunction of sex chromosomes- turners syndrome, klinefelter's syndrome, Triple XXX syndrome. 

Term
What are monosomics?
Definition
They are humans who have lost even one copy of an autosome, through nondisjunction. Generally monosomic individuals do not survive embryonic development. 
Term
What is x-inactivation?
Definition
X- inactivation happens when one of the two x chromosomes of the female shuts down by packaging into transcriptionally inactive heterochromatin. This happens so that females do not have twice as many x-chromosome gene products as males do. Inactivation is random when choosing which chromosome will be inactivated.
Term
what does trisomy mean? and what usually happens if a human is trisomic?
Definition

Trisomy is when nonsdisjunction gives you an extra autosome. This results in death most commonly, howevers some autosomes can be present as three copies and still allow the individual to survive, at least for a time. 

one trisomy is down syndrome. 

Term
What can result from nondisjunction of sex chromosomes?
Definition

X chromosome nondisjunction: 

XXX- develops into a female with one functional X chromosome and two barr bodies. She may be taller in stature but otherwise is normal.

XXY- develops into a male who has many female body characteristics, and, in some cases but not all, diminished mental capacity. (Klinefelters syndrome). 1/500 male births

OY- fails to develop 

0X- develops into a sterile female of short stature, with a webbed neck and sex organs that never fully mature during puberty. Mental abilities= low-normal range. (Turners Syndrome) 1/5000 female births

Y chromosome nondisjunction:

XYY- develop into fertile males of normal appearance. (Jacobs syndrome) 1/1000 newborn babies

Term
What is a barr body?
Definition
An inactivated condensed chromosome
Term
What do calico cats have to do with X inActivation?
Definition
They are an example of how X inactivation can lead to genetic mosaics if the female is heterozygous for x chromosome alleles. 
Term
How can an XX embryo develop as a male?
Definition
If part of the Y chromosome translocated to one of the x chromosomes, the embryo will develop as a male. 
Term
What are some examples of genetic disorders that are sex linked?
Definition
Color blindness, and hemophilia. Sweat glands and orange fur in calico cats. 
Term
How can X chromosome inactivation lead to genetic mosaics?
Definition
Females that are heterozygous for X chromosome alleles are genetic mosaics: their individual cells may express different alleles depending on which chromosomes are inactivated. 
Term
Explain how the fur of a calico cat is colored based on X inactivation?
Definition
A female that has patchy distribution of dark fur, orange fur, and white fur has dark and oragne fur due to heterozygosity for a gene on the x chromosome that determine pigment type. One allele results in dark fur, and another allele results in orange fur. Which of these colors is observed in any particular patch is due to inactivation of one X chromosome. 
Term
What is polyploidy, and when does it occur?
Definition
It occurs in metaphase I of Meiosis. Polyploidy is when an organism has more than two paired homologous sets of chromosomes (diploid). 
Term
How many paired homologous sets of chromosomes should an organism have?
Definition
Two, diploid
Term
What is haploidy, and is haploidy possible?
Definition
It is when a organism only has one paired set of chromosomes. Some organisms may go through a haploid phase as a normal phase of life. 
Term
What organisms tolerate polyploidy?
Definition
Some animals such as salmon, goldfish, and salamanders. Mainly ferns and flowering plants are polyploid. Also occcurs normally in some animal tissues, such as the human muscle tissue
Term
What is a zinc finger protein
Definition

-A regulatory protein, named "finger" protein because it is coiled up to look like fingers

-Example, in males that have XX's is responsible for the binding of the crucial chunk from the Y that crosses over to the X during prophase

-function is to bind DNA, RNA, proteins or small molecules.  

- Has 13 fingers

Term
what does aneuploidy mean
Definition

-an abnormal number of chromosomes

-occurs during cell division

-

Term
What is the result of a female that has extra X's (XXX, XXXX)
Definition
-She could have fertility problems
Term
What does the word ending "somy" mean
Definition

Chromosome

-monosomy= 1 (deletion on one, example turners syndrome)

-disomy=2 (normal)

-trisomy = 3 (famous example is downs syndrome, also known as trisomy 21)

-tetrasomy=4

Term
What does the word ending "ploidy" mean
Definition

the number of complete set of chromosomes

-monoploid (number of unique chromosomes in a single complete set)

-diploid (normal number of sets)

-triploid (occurs in a lot of plants but not humans)

Term
What is the haploid number?
Definition

- The one complete set of chromosomes necessary to define an organism

-For humans the haploid number is 23

Term
What is the diploid number?
Definition

-The normal number of chromosomes in a cell (twice the amount of the haploid #)

-is 46 for humans 

Term
What is a karyotype 
Definition
The particular array of chromosomes that an individual possesses 
Term
What is a homologue?
Definition

One of a pair of chromosomes of the same kind located in a diploid (2n) cell; one copy of each pair of homologous comes from each gamete that formed the zygote. 

 

Term
what is an emerging virus?
Definition

-A virus that originate in one organism and then pass to another and cause disease.

-Example HIV, said to have been from chimpanzees

-Influenza is fundamentally a bird virus

Term
Flu viruses
Definition

-segmented RNA viruses

-Combination of hemagglutinn (aids the virus in in gaining access to the cell interior) and neuraminidase (helps the daughter viruses break free of the host cell once virus replication has been replicated)

-Recombination of the virus makes it difficult to form natural immunity and vaccines

Term
Cancer
Definition

-Viruses may contribute to about 15% of all human cancer cases worldwide 

-Ex. link between chronic hep B infections and the development of liver cancer, link between cervical cancer and HPV

Term
What are viroids?
Definition

-Tiny naked molecules of circular RNA that are infectious disease agents in plants. 

-It is unknown as to why viroids cause disease 

 

Term
What is the basic structure of a virus?
Definition
- A core of nucleic acid surrounded by a protein 
Term
True or False, Viruses have a limited host range and many also exhibit tissue tropism?
Definition
True
Term
What is tissue tropism?
Definition

-it is where the virus only attacks a specific set of cells

-Rabies for example, grows in neurons and hepatitis replicates liver cells

Term
How do viruses replicate?
Definition
-They take over the host machinery and direct their own nucleic acid replication and and protein synthesis
Term
Why are viruses obligate intracellular parasites?
Definition
-because they lack ribosomes and proteins needed for replication
Term
What is a retrovirus?
Definition

-A virus that contains an RNA that that is transcribed into DNA by reverse transcriptase

-HIV/AIDs is an example

Term
What are Bacteriophages?
Definition

-Highly variable viruses that only infect bacteria (bacterial cells)

-also known as phage

Term
What are the two reproductive cycles that bacterial viruses exhibit 
Definition

1. The lytic cycle, kills the host cell

2. The lysogenic cycle where the virus is incorporated into the host genome as a prophage

Term
For most phage, what steps of infection are there?
Definition

-Injection of DNA

-macromolecular synthesis

-assembly of a new phage

-release of progeny phage

Term
what is a prion?
Definition

-infectious particles that misfolded protiens that serve as templates for normal proteins to misfold

-they are responsible for transmissable spongioform encepalopathies

Term
How are bacterial diseases spread?
Definition
through mucus or saliva droplets, contaminated food and water, and insect vectors. 
Term
Give some examples of bacterial diseases.
Definition
Ulcers, sexually transmitted diseases (Gonorrhea, syphilis, and chlamydia). Tuberculosis. 
Term
What are some ways that bacteria can live in symbiosis with eukaryotes?
Definition

Usual relationship.

Nitrogen fixing bacteria and plant roots (mutualism)

bacteria in digestive tracts of animals, cows they digest cellulose. 

humans in large intestine they produce vitamins

Outer surgace of animals and plants, do not cause damage. (commmensalissm)

Bacterial infection is a form of parasitism in a sense. 

Term
How are bacteria used in genetic engineering?
Definition

A gene from a human can be inserted into a bacterial cell, and the bacterium will produce a human protein. 

Bacterias are also now widely used as "biofactories" in the commerical production of variety of enzymes, vitamins, and antibiotics. 

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