Chapter 4: Genes and Cellular Function

True or false: There are no genes for glycogen, fat, steroids, phospholipids, and many other compounds, yet their synthesis is under indirect genetic control.

True

Recall that the start codon is AUG. Based on this, the initiator tRNA will always have which anticodon?

UAC

When do cells divide?

When neighboring cells die, opening up space in a tissue to be occupied by new cells When they have replicated their DNA, so they can give each daughter cell a duplicate set of genes When they grow large enough to have enough cytoplasm to distribute to their two daughter cells

Which of the following is a true statement?

Which proteins a cell makes is determined by which genes are activated in that cell.

The protein that guides newly synthesized proteins in folding into their proper shape and helps to prevent improper associations between different proteins is a ___.

chaperone

In the nucleus, DNA is complexed with proteins to form a fine filamentous material called ___.

chromatin

In the nucleus of a dividing cell, the chromatin condenses so that each ___, now made of two sister chromatids, can be seen with a light microscope.

chromosome

A three-base sequence of mRNA is called a(n) ___.

codon

The division of the cytoplasm to form two cells is called ___.

cytokinesis

Cytokinesis is the division of the cell's ___ to form two cells.

cytoplasm

Where is RNA usually found?

cytoplasm

The basic unit of a nucleic acid is shown in this picture. It is called a ___ and it has three components: a phosphate group, a sugar (like deoxyribose), and a nitrogenous base (like adenine).

nucleotide

A cluster of several ribosomes (illustrated in the figure labeled A) reading one mRNA during translation is called a ___.

polyribosome, polysome

The nuclear envelope is perforated with openings called nuclear ___ that regulate the movement of molecules through the envelope.

pore

During the mitotic phase called ___, chromosomes condense, the nuclear envelope disappears, spindle fibers grow, and centrioles migrate to the poles of cell.

prophase

Indicate which of the following are functions of mitosis.

It allows growth of all tissues and organs after birth. It repairs damaged tissues. It allows development of an individual, composed of some 50 trillion cells, from a one-celled fertilized egg. It replaces the cells that die with new ones.

What is the role of mRNA in protein synthesis?

It carries the genetic code from the nucleus to the cytoplasm.

When synthesized proteins are to be exported out of the cells, they are packaged into secretory vesicles that originate in what organelle?

Golgi complex

During the cell cycle, G1, S, and G2 collectively make up the phase known as what?

Interphase

Which of the following are characteristics of ribonucleic acid (RNA)?

It leaves the nucleus and can be found in the cytoplasm. It plays an important role in the production of proteins. It contains nitrogenous bases A, U, C, G.

How does newly synthesized mRNA pass from within the membrane-bound nucleus into the cytosol?

It passes through nuclear pores.

Which of the following statements are true concerning the first tRNA to bind to a ribosome at the the start of translation?

Its anticodon is complementary to the codon AUG (the start codon). It is called the initiator tRNA.

Indicate which of the following is NOT part of interphase.

M

Place the phases of the cell cycle in the correct order starting with G1.

1. G1 2. S 3. G2 4. M

Translation occurs in three steps. Place these steps in chronological order.

1. Initiation 2. Elongation 3. Termination

Place the steps of translation in the correct order, starting with what happens first.

1. The ribosome binds mRNA 2. A tRNA anticodon binds to a complementary mRNA codon 3. A new amino acid chain is linked to the growing peptide chain 4. The tRNA is released from the ribosome and is now available to pick up another amino acid

Put the steps of mitosis in the correct order. When you are done, the first step should be at the top, and the last step should be at the bottom.

1. prophase 2. metaphase 3. anaphase 4. telophase

Describe chaperones.

1.They help prevent improper associations between different proteins. 2.Some are also known as stress proteins or heat shock proteins. 3.They aid a newly synthesized protein in folding to its proper shape.

Describe the events that occur during the synthesis (S) phase of the cell cycle.

A cell makes a duplicate copy of its centrioles and all of its nuclear DNA.

Which of the following statements about codons are true?

A codon is a three-base sequence of mRNA. The genetic code is expressed as a sequence of codons.

Which molecules are indicated by the arrow labeled A?

Amino acids

This circle is divided into lettered quadrants. Each one represents a phase of the cell cycle. Match the letter of each quadrant with the cell cycle phase that it represents. Instructions

A---M - Mitotic phase B---G1 - 1st gap phase (growth and normal metabolic roles) C--- S Phase - Synthesis phase (DNA replication) D---G2 - 2nd gap phase (growth and preparation for mitosis)

Match the letter indicated in the figure with the name of the structures participating in DNA replication.

A---Parental DNA B---Daughter DNA C---DNA polymerase D---DNA helicase E---DNA ligase

Which of these demonstrate accurate base pairing according to the law of complementary base pairing?

A-T

Which two nitrogenous bases are classified as purines?

Adenine Guanine

Refer to the table. The genetic code uses the mRNA codon GCA to indicate which of the following amino acids?

Alanine

Daughter chromosomes migrate to opposite poles of the cell during which phase of mitosis?

Anaphase

Which of the following refers to a 3-base sequence found in tRNA?

Anticodon

Following transcription, only some portions of the mRNA code for the final protein. The sections of mRNA that contain necessary code are called ___, whereas the mRNA sections that do not code for the final protein are called ___.

Blank 1: exons Blank 2: introns

Refer to the table. Match the base triplet of DNA to the amino acid specified by the genetic code.

CCA---Glycine CGT---Alanine TGC---Threonine GTA ---Histidine

Indicate which of the following events occur during prophase of mitosis. Select all that apply.

Centrioles are pushed apart. Chromosomes condense. Nuclear envelope disappears. Spindle fibers grow from the centrioles.

Which term refers to the filamentous material composed of DNA and associated proteins that is found in the nucleus of a cell?

Chromatin

In the nucleus of a typical human cell, there are 46 DNA filaments. Which term refers to one of these structures?

Chromosome

Transcription is the process of copying genetic instructions from a molecule of ___ to mRNA.

DNA

Match each protein with its role during DNA replication.

DNA helicase---Opens the DNA helix exposing the nitrogenous bases DNA polymerase---Reads nitrogenous bases and matches them with complementary free nucleotides DNA ligase--- Joins the newly synthesized segments of DNA

Which molecules participate in DNA replication?

DNA polymerase DNA DNA ligase DNA helicase

Which of the following occurs during anaphase?

Daughter chromosomes migrate to opposite ends of the cell.

Which of the following events occur after a protein is synthesized?

Enzymes in the ER may modify the protein through posttranslational modification. The Golgi complex may modify the protein by adding carbohydrate chains. A chaperone may guide the protein in folding into the proper shape.

True or false: Cells start dividing when they snugly contact neighboring cells or when growth factors are withdrawn.

False

True or false: Genes produce their products nonstop, 24-hours a day.

False

True or false: Proteins that must be packaged into a lysosome or secreted from the cell are synthesized in free ribosomes.

False

Which phase is an interval between cell division and DNA replication? During this time, a cell synthesizes proteins, grows, and accumulates the materials needed to replicate its DNA in the next phase.

G1

Which phase is a short period of time of growth and preparation for mitosis? During that time, the cell produces enzymes that control cell division, and also checks and repairs the newly copied DNA.

G2

Which of the following terms refers to a segment of DNA that codes for the production of a molecule of RNA?

Gene

Since there are no genes coding for carbohydrates, nucleic acids, or lipids, how do cells produce them?

Genes encode enzymes that synthesize these products.

Alternative splicing helps explain which of the following?

How one gene can produce more than one protein

Where does the making of mRNA from DNA take place?

In the nucleus

The first tRNA to bind to a ribosome at the start of translation is known as what?

Initiator tRNA

In which of the following subdisciplines of genetics are family relationships analyzed to predict patterns of inheritance within a family line?

Mendelian genetics

The chromosomes are seen as fully aligned on the cell equator during which phase of mitosis?

Metaphase

A cell replicates its nucleus and then forms two new daughter cells during which phase of the cell cycle?

Mitotic phase (M)

What are the monomeric subunits that comprise a molecule of DNA called?

Nucleotides

Where does translation take place?

On a ribosome

This figure illustrates the mechanism of alternative splicing. What is its result?

One gene can code for more than one protein.

One mRNA can have several ribosomes attached to it at one time during translation of mRNA. Which term refers to this cluster of ribosomes?

Polyribosome

Which molecule contains introns and exons?

Pre-mRNA

Name the correct order of the phases of mitosis from beginning to end.

Prophase, metaphase, anaphase, telophase

Which enzyme is responsible for transcribing DNA?

RNA polymerase

The process by which a cell makes a copy of its DNA, creating two new strands is referred to as which of the following?

Replication

The law of complementary base pairing states that a cell can do which of the following?

Reproduce one strand of DNA based on information in the other

Indicate the events that occur during translation.

Ribosome binds messenger RNA (mRNA). Transfer RNA (tRNA) anticodon binds to complementary mRNA codon. Transfer RNA (tRNA) delivers an amino acid to the ribosome. A new amino acid is linked to the growing peptide chain.

Name the period of synthesis during which a cell makes a duplicate copy of its centrioles and all of its nuclear DNA.

S phase

Golgi vesicles containing proteins to be released from the cell will become which type of vesicle?

Secretory

After DNA replication, each daughter DNA consists of one new helix synthesized from free nucleotides and one old helix conserved from the parental DNA. What is this process called?

Semiconservative replication

Which of the following are components of nucleotides?

Sugars (ribose or deoxyribose) Phosphate groups Nitrogenous bases

What occurs during the G2 phase of the cell cycle?

The cell synthesizes enzymes that control cell division and also checks and repairs the newly copied DNA.

What occurs during the G1 phase of the cell cycle?

The cell synthesizes proteins, grows, and accumulates the materials needed to replicate its DNA in the next phase.

Which of the following statements are true regarding the DNA structure? Select all that apply.

The nitrogenous bases face the inside and hold the two backbones together with hydrogen bonds. Each sidepiece is a sugar-phosphate backbone composed of phosphate groups alternating with the sugar deoxyribose. The basic three-dimensional structure of DNA is the double helix.

Which of the following can be considered the essential function of RNA?

To use the instructions coded in DNA to synthesize proteins

The enzyme RNA polymerase participates in which of the following processes?

Transcription

Which term refers to the process of copying the information encoded in DNA into RNA?

Transcription

Which term refers to the step of protein synthesis in which DNA is used to make mRNA?

Transcription

The molecule shown in this figure plays an important role in which of the following processes?

Translation

Which term refers to the conversion of nucleotide sequences into amino acid sequences?

Translation

___ occurs in three steps called initiation, elongation, and termination.

Translation

True or false: It is possible to predict the sequence of one strand of DNA if we know the sequence of the complementary strand.

True

At one end of each tRNA there is a sequence of three nucleotides known as the ___ . This sequence is complementary to the bases on mRNA.

anticodon

At one end of each tRNA there is a sequence of three nucleotides known as the ___. This sequence is complementary to the bases on mRNA.

anticodon

A(n) ___ is an information-containing segment of DNA that codes for the production of a molecule of RNA, and that in most cases codes for one or more proteins.

gene

When a woman gives birth the hormone prolactin stimulates her mammary glands to produce casein, a protein that her body has never synthesized before. This demonstrates which of the following?

genes can turn on and off

Which molecule carries the genetic code from the nucleus to the cytoplasm?

mRNA

The form of cell division in which a cell divides once and produces two genetically identical daughter cells is known as ___.

mitosis

During metaphase, the spindle fibers form a lemon-shaped array called the ___ spindle.

mitotic

When a cell replicates its nucleus and then pinches in two to form two new daughter cells it is said to be in the M phase, also called the ___ phase, of the cell cycle.

mitotic, mitosis

Any change in the structure of a chromosome or a DNA molecule, often resulting in a change of structure or function in the protein produced, is known as a(n) ___.

mutation

Exposure to chemicals and radiation may lead to changes in DNA structure called ___.

mutation

The process by which a cell makes a copy of its DNA so it can give complete and identical copies of all of its genes to each daughter cell is DNA ___.

replication

When a protein must be exported outside the cell, it is synthesized in ribosomes bound to the ______ (indicated by a "A"). Then it is modified and packaged into a ______ (indicated by "B").

rough endoplasmic reticulum, transport vesicle

There are no genes that directly code for ______.

steroids phospholipids glycogen

Anticodons are found on which type of molecule?

tRNA

In DNA, the base adenine pairs with the base ___.

thymine, T