Test 4- Ch 12.13.16.17. Flashcards
The centromere is a region in which
Chromatids remain attached to one another until anaphase
Suppose a biologist can seperate one of the dozen pieces of chromatin from a eukaryotic, animal, nucleus. It might consist of which of the following?
Two long strands of DNA plus proteins
At which phase are centrioles beginning to move apart in animal cells
Prophase
Movements of the chromosomes during anaphase would be most affected by a drug that prevents
Shortening of micro tubules
Measurements of the amount of DNA Per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels range from 3 to 6 picograms per nuclear. In which stage of the cell cycle did the nucleus contain six pico grams of DNA?
G2
During which phase of mitosis did the chromatids become chromosomes?
Anaphase
What is a cleavage furrow?
A groove in the plasma membrane between daughter nuclei
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
Cycling
Density-dependent inhibition is explained by which of the following
Add cell become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing
Is a horticulturists breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants?
Clone the plant asexually to produce an identical one
The human genome is minimally contained in which of the following?
Every human cell
In the human species, all somatic cells have 46 chromosomes. Which of the following can also be true?
A plant Species (privets shrubs? has 46 chromosomes per cell
Which of the following is a true statement about sexual versus asexual reproduction
In sexual reproduction, individuals transmit 50% of their genes to each of their offspring
The human X and Y chromosomes
Include genes that determine an individuals sex
Which of the following is true of a species that has a chromosome number of 2n= 16?
Each cell has eight homologous pairs
Eukaryotic sexual lifecycles show tremendous variation of the following elements which do sexual lifecycles have in common
Meiosis, fertilization and Gametes
They karyotype of one species of primate has 48 chromosomes. In a particular female cell division goes awry and she produces one of her eggs with an extra chromosome 25 the most probable source of this error would be a mistake in which of the following?
Either anaphase one or two
A karyotype results from which of the following?
The ordering of human chromosome images
If a cell has completed the first meiotic division And it just begins miosis two, which of the following is an appropriate description of its contents
It has half the amount of DNA as the cell that began meiosis
In the human karyotype chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following to the two chromosomes of the pair have in common
Length centromere position staining pattern and traits coded for by their genes
Which of the following occurs in meiosis but not in mitosis
Synopsis of chromosomes
Independent assortment of chromosomes is a result of
The random and independent way in which each pair of homologous chromosomes line up at the metaphase plate during meiosis one
In his transformation experiments, what did Griffith observe
Mixing a heat killed pathogenic strain of bacteria with the living nonpathogenic strain can convert some of the living cells into the pathogenic form
Cytosine makes up 42% of the nuclear tides in a sample of DNA from an organism approximately what percentage of the nuclear tides in the sample will be thymine
8%
And analysis of the nucleotide composition of DNA which of the following will be found
A+C=G+T
What is meant by the description antiparallel regarding the strands that make up DNA
The 5’ to 3’ Direction of one strand runs counter to the five prime to three prime direction of the other strand
What does the enzyme telomerase Meet the challenge of replicating the ends of linear chromosomes?
It catalyzes the lengthening of telomeres, compensating for the shortening that occurs during replication
What is the function of DNA polymerase III?
To add nuclear tides to the three prime end of the growing DNA strand
The difference between ATP and the nucleoside triphospates used during DNA synthesis is that
The nucleoside triphospates have the sugar deoxyribose; ATP has the sugar ribose
The leading and the lagging strands differ in that
The leading strand is synthesized in the same direction as the movement as the replication fork and the lagging strand is synthesized in the opposite direction
A new DNA strand elongates only in the 5’ to 3’ direction because
DNA polymerase an only add nucleotides to the free 3’ end
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
It joins Okasaki fragments together
The nitrogenous base adenine is found in all members of which group?
ATP, RNA, and DNA
A particular triplet of bases in the template strand of DNA is 5’ AGT 3’. The corresponding coding for the mRNA transcribed is
3’ UCA 5’
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A gene from an organism can theoretically be expressed by any organism
Which of the following provides some evidence that RNA probably evolved before DNA?
DNA polymerase uses primer, usually made of RNA
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
Any mutation in the sequence is selected against
What is a ribozyme?
an RNA with enzymatic activity
A eukaryotic transcription unit that is 8,000 nucleotides long may use 1200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that
Many noncoding stretched of nucleotides are present in eukaryotic DNA
In an experimental situation. a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5’ cap and poly-A tail. Which of the following would you expect him to find?
The molecule is digested by exonucleases since it is no longer protected by at the 5’ end
Accuacy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
When the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?
Its signal sequence must target it to the ER, from which it goes to the Golgi
Why might a point mutation in DNA make a difference in the level of a protein’s activity?
It might substitute a different amino acid in the active site
What is the effect of a nonsense mutation in a gene?
It introduces a premature stop codon into the mRNA
