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anatomy and physiologie exam prep : biomechanics, Quizzes of Anatomy

The resting potential of the cell membrane and the process of cell cycle, including mitosis and meiosis. It explains the composition of chromosomes, DNA, and RNA, and how they are involved in protein synthesis. The document also provides multiple-choice questions and answers related to the topics.

Typology: Quizzes

2022/2023

Available from 07/18/2023

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92. The cell membrane’s resting potential (about 70 mV inside with respect to the
outside) is due mainly to which of the following mechanisms?
A. The sodium potassium pump.
B. The diffusion of cations and anions through the membrane along their con-
centration gradients.
C. The diffusion of sodium and potassium across the cell membrane.
D. The presence inside the cell of anions too large to passively cross the cell
membrane.
Answer is A: The ATPase pump shifts 3 Na
+ out of the cell and 2 K
+ into the
cell. This disparity in positive charge is the major infl uence on the resting
potential.
2.2 Cell Cycle (Mitosis and Protein Synthesis)
The cell nucleus contains chromosomes which are composed of molecules of
DNA. DNA is composed of units called nucleotides which consist of a sugar (deoxy-
ribose) attached to a phosphoric acid group (PO
3 OH) and one of four bases.
Chromosomes contain the code for the sequence of amino acids used to construct
different proteins. Each amino acid is coded for by a particular sequence of three of
the four bases (adenine, guanine, cytosine & thymine). This sequence is called a
“codon”. mRNA “transcribes” this code then moves from the nucleus to a ribosome
in the cytoplasm where it is “translated” and the protein is assembled by joining the
required amino acids in the appropriate sequence.
Mitosis is the process by which a somatic cell divides to produce two cells with
identical DNA. In this way an organism can grow. Before mitosis, the DNA must be
duplicated. Hence the chromosomes (consisting of one strand or “chromatid”) dou-
ble up by becoming two chromatids. Then during mitosis the two chromatids sepa-
rate and move into the two daughter cells.
Meiosis occurs only in the gonads. This process results in four daughter cells.
Human cells have two copies of each of 23 chromosomes, one copy being inherited
from the father and the other copy from the mother. The gametes need to have only
one copy of each of the 23 chromosomes, so that when the sperm fuses with the
ovum, the “diploid” number of 46 (two copies of each chromosome) is restored.
Meiosis is the process by which cells reduce their number of chromosomes from 46
to 23 different chromosomes. Of the 23 chromosomes in a sperm (or ovum), some
(between 0 and 23) will have come from the sperm owner’s mother and the rest from
the sperm owner’s father. The same can be said of the 23 chromosomes in the ovum.
In this way the resulting children will be genetically different from each of their
parents (and siblings) as each sperm/ovum will have a different assortment of the 23
available chromosomes.
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  1. The cell membrane’s resting potential (about −70 mV inside with respect to the outside) is due mainly to which of the following mechanisms? A. The sodium potassium pump. B. The diffusion of cations and anions through the membrane along their con- centration gradients. C. The diffusion of sodium and potassium across the cell membrane. D. The presence inside the cell of anions too large to passively cross the cell membrane. Answer is A: The ATPase pump shifts 3 Na+^ out of the cell and 2 K+^ into the cell. This disparity in positive charge is the major influence on the resting potential.

2.2 Cell Cycle (Mitosis and Protein Synthesis)

The cell nucleus contains chromosomes which are composed of molecules of DNA. DNA is composed of units called nucleotides which consist of a sugar (deoxy- ribose) attached to a phosphoric acid group (PO3OH) and one of four bases. Chromosomes contain the code for the sequence of amino acids used to construct different proteins. Each amino acid is coded for by a particular sequence of three of the four bases (adenine, guanine, cytosine & thymine). This sequence is called a “codon”. mRNA “transcribes” this code then moves from the nucleus to a ribosome in the cytoplasm where it is “translated” and the protein is assembled by joining the required amino acids in the appropriate sequence. Mitosis is the process by which a somatic cell divides to produce two cells with identical DNA. In this way an organism can grow. Before mitosis, the DNA must be duplicated. Hence the chromosomes (consisting of one strand or “chromatid”) dou- ble up by becoming two chromatids. Then during mitosis the two chromatids sepa- rate and move into the two daughter cells. Meiosis occurs only in the gonads. This process results in four daughter cells. Human cells have two copies of each of 23 chromosomes, one copy being inherited from the father and the other copy from the mother. The gametes need to have only one copy of each of the 23 chromosomes, so that when the sperm fuses with the ovum, the “diploid” number of 46 (two copies of each chromosome) is restored. Meiosis is the process by which cells reduce their number of chromosomes from 46 to 23 different chromosomes. Of the 23 chromosomes in a sperm (or ovum), some (between 0 and 23) will have come from the sperm owner’s mother and the rest from the sperm owner’s father. The same can be said of the 23 chromosomes in the ovum. In this way the resulting children will be genetically different from each of their parents (and siblings) as each sperm/ovum will have a different assortment of the 23 available chromosomes.

  1. The term “chromatin” would be used in reference to which of the following?

A. genetic substance B. cellular energy C. membrane support D. nuclear membrane Answer is A: Chromatin is DNA & the associated proteins so pertains to genetic material.

  1. In protein synthesis, where dose translation occur? In the:

A. cytoplasm between ribosomes, tRNA and mRNA B. nucleus between ribosomes, tRNA and mRNA C. nucleus between DNA and mRNA D. cytoplasm between DNA and mRNA Answer is A: translation occurs in the cytoplasm (transcription occurs in the nucleus). DNA does not exist in the cytoplasm.

  1. If the DNA strand sequence of bases is CTT AGA CTA ATA, what would the tRNA read? A. GAA TCT GAT TAT B. CUU AGA CUA AUA C. GAA UCU GAU UAU D. GUU ACA GUA AUA Answer is C: guanine (G) must be matched to cytosine (C) and vice versa. Adenine (A) must match with thymine (T). In RNA, uracil (U) replaces thy- mine, while both bind to adenine. Hence U must be matched to A.
  2. Which one of the following statements best describes DNA?

A. single stranded, deoxyribonucleic acid B. single stranded, ribonucleic acid C. double stranded, deoxyribonucleic acid D. double stranded, ribonucleic acid Answer is C: DNA is double stranded, while the “D” refers to “deoxy-”.

  1. In which phase of mitosis would chromosomes line up at the centre of the spindle: A. anaphase B. interphase C. prophase D. metaphase Answer is D: Remember the metaphase plate occupies the middle of the cell.

C. A codon D. A nucleotide Answer is D: three nucleotides form a codon and many codons form a chromatid.

  1. What happens during anaphase of mitosis?

A. spindle fi bres pull each chromatid to opposite sides of the cell B. the sense and non-sense strands “unzip” along their hydrogen bonds C. RNA polymerase forms a complementary strand by reading the sense strand D. the cell cytoplasm divides into two cells Answer is A: separation of the two chromatids of a chromosome occurs at ana- phase. Choice D is cytokinesis and begins in late anaphase and continues into telophase.

  1. The process by which information is read from DNA, encoded and transported outside the nucleus is known as: A. translation B. transcription C. encoding D. catalysis Answer is B: to “transcribe” is to record the information from a source and to record it at another place (onto mRNA). Then messenger RNA moves out of the nucleus
  2. How many nucleotides are required to code for a single amino acid?

A. twenty B. fi ve C. three D. one Answer is C: A sequence of three nucleotides constitute a codon. Each codon is specifi c for one of the 20 amino acids.

  1. The combination of a sugar, a base and at least one phosphate group is given the general term of: A. nucleoside B. amino acid C. polypeptide D. nucleotide Answer is D: a nucleoside is a nucleotide without a phosphate group.
  1. The nucleus of the cell contains the master nucleic acid:

A. DNA B. RNA C. mRNA D. tRNA Answer is A: DNA exists in the nucleus. The other three are ribonucleic acids.

  1. Which of the following is the correct combination of the components for the nucleic acid DNA? A. Phosphate, Ribose, Uracil B. Phosphate, Deoxyribose, Proline C. Phosphate, Ribose, Thymine D. Phosphate, Deoxyribose, Adenine Answer is D: DNA has the sugar deoxyribose, proline is an amino acid that does not occur in DNA.
  2. In the ribosome of a cell, the mRNA is read to produce the particular amino acid sequence for the formation of a protein. What is this process called? A. Translation B. Transcription C. Transportation D. Transmutation Answer is A: translation occurs in the cytoplasm of a cell with a ribosome. It is when the information in mRNA is read to produce the sequence of amino acids needed to form a protein.
  3. Which of the base pairings in DNA would be correct?

A. A–T pair B. A–G pair C. C–T pair D. C–A pair Answer is A: A pairs with T, while C pairs with G.

  1. The combination of a sugar and a base is given the general term of:

A. nucleoside B. amino acid C. polypeptide D. nucleotide Answer is A: a nucleotide is formed from a nucleoside and a phosphate group.

cells – 23 each from the man’s father and mother. When sperm are produced, the 46 chromosome assemble and pair up. The man’s X and Y chromosomes pair up. Each pair of chromosomes then separates so that only one of each pair moves into a new sperm. Which one of the pair ends up in which sperm is a random process. It is possible that an individual sperm has any number of chro- mosomes between 0 and 23 that originated from the father.