Biology 101 Hinton Exam 4

prometaphase

2nd phase, Nuclear envelope breaks down, microtubles start to invade, kinetochores form

G1, S(synthesis), G2

3 phases of interphase

metaphase

3rd phase, centrosomes at complete other side, metaphase plate, line up

anaphase

4th phase, cohesion proteins have to be broken down, sister chromatids can now seperate, cell elongates

Either an insertion or a deletion of a base.

A frameshift mutation could result from __________

Its gametes must have 23 chromosomes.

A given organism has 46 chromosomes in its karyotype. We can therefore conclude what?

The ordering of human chromosome images.

A karyotype results from what?

UUU.

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is ___________

3' UCA 5'.

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is what?

3' AAA-GAA-TAA-CAA 5'.

A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be _________

Many noncoding stretches of nucleotides are present in mRNA.

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that __________

Haploid, and the chromosomes are each composed of two chromatids.

After telophase I of meiosis, the chromosomal makeup of each daughter cell is ______

Metaphase

At what stage is a karyotype produced?

II, III, and IV

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. alternation of generations II. meiosis III. fertilization IV. gametes V. spores

Prophase

First phase , chromatin start to condense down to form chromosomes, sister chromatids start pairing, mitotic spindles, centrosomes start moving away

In mitosis, each daughter cell receives complete copy of chromosomes; in meiosis, each daughter cell recieves two copies of half genome. In mitosis, chromosome number stays same; in meiosis, chromosome number is reduced by half.

How are mitosis and meoisis compared?

RNA has a greater rate of error because they have no proofreading systems. Can begin synthesis de novo (does not need a primer), which is why its significant to make a mistake in RNA b/c it can be degraded.DNA is the master copy, so it cannot make mistakes.

How does RNA polymerase differ from DNA polymerase?

The tRNA that was in the A site moves into the P site.

If a ribosome travels along a mRNA molecule by 1 codon, what will happen?

Zygotes.

In animals, meiosis results in gametes, and fertilization results in _____________

Gametes.

In animals, somatic cells are produced by mitosis and ________ are produced by meiosis.

telophase & cytokinesis

Last phase of mitosis, reformation of two cells, actual separation of cytoplasm, nuclear envelope reform, see nucleoli again

Separates homologous chromosomes.

Meiosis I

Separates sister chromatids

Meiosis II

Removal of introns.

Once transcribed, Eukaryotic messenger RNA under goes a lot of alteration. What does it include?

-People with SCD have abnormal hemoglobin, called hemoglobin S or sickle hemoglobin, in their red blood cells. -Hemoglobin is a protein in red blood cells that carries oxygen throughout the body. -Inherited -Sickle-shaped cells are not flexible and can stick to vessel walls, causing a blockage that slows or stops the flow of blood. oxygen can't reach nearby tissues.

Sickle cell disease

One mutated tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.

Suppose that a mutation alters the formation of a tRNA such that it still attaches to the same amino acid (phe) but its anticodon loop has the sequence AAU that binds to the mRNA codon UUA (that usually specifies leucine leu)

If UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only).

The "universal" genetic code is now known to have exceptions. Evidence for this can be found if what is true?

A gene from an organism can theoretically be expressed by any other organism.

The genetic code is essentially the same for all organisms. From this, one can logically assume what?

ATP, RNA, and DNA

The nitrogenous base adenine is found in all members of what group?

The rules for base pairing between the third base of a codon and tRNA are flexible.

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that __________

5' UTR E₁ E₂ E₃ E₄ UTR 3'

Use the following model of a eukaryotic transcript to answer the next few questions. 5' UTR E₁ I₁ E₂ I₂ E₃ I₃ E₄ UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol?

Region where the identical DNA molecules are most tightly attached to each other.

What are centromeres?

Groups of ribosomes reading a single mRNA simultaneously.

What are polyribosomes?

Interphase, Prophase, Metaphase, Anaphase, Telophase

What are the phases of mitosis in their proper sequence?

A plant like protist

What can utilize both mitosis and meiosis in the correct circumstances?

A display of each of the chromosomes of a single cell.

What describes a karyotype?

Meiosis and Fertilization

What do all sexual life cycles have in common?

A cell (zygote) capable of undergoing cell division to form a new individual.

What does fertilization result in?

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

What does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?

The haploid set of chromosomes in a gamete or microorganism.

What is a genome?

Locations of genes on chromosomes.

What is a loci?

An RNA with enzymatic activity.

What is a ribozyme?

Small Nuclear RiboNucleo Proteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs.

What is a snRNP("snurp")?

A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.

What is a tetrad?

In sexual reproduction, individuals transmit 50% of their genes to each of their offspring.

What is a true statement about sexual vs. asexual reproduction?

An alternat version of a gene, two per character.

What is an allele?

Physical division of the cell

What is mitosis?

It introduces a premature stop codon into the mRNA.

What is the effect of a nonsense mutation in a gene?

The small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA.

What is the first event to take place in translation in eukaryotes?

mRNA.

What is the most abundant type of RNA?

The flexible base pairing at tRNA codon positioning.

What is wobble?

Synapsis of chromosomes.

What occurs in meiosis but not in mitosis?

DNA polymerase uses primer, usually made of RNA.

What provides some evidence that RNA probably evolved before DNA?

Prophase I of meiosis.

When does synapses occur when crossing over?

Late prophase of meiosis I.

When does the synaptonemal complex disappear?

As soon as transcription has begun.

When does translation begin in prokaryotic cells?

It might substitute an amino acid in the active site.

Why might a point mutation in DNA make a difference in the level of protein's activity?