Chapter 2: The Cell, Structure and Funciton

during which stage does the nuclear envelope start to disintegrate

During prophase, the chromosomes condense, the nucleolus disappears, and the nuclear envelope breaks down.

Which of these is the function(s) of nucleotides? a) they are the monomers for production of nucleic acids b) they have energy carrying functions c) they have cell signaling functions d) all of the above

D

replication of DNA occurs during

interphase

microfilaments provide structural support for hairlike projections of the plasma membrane called _____

microvilli

Triglycerides are ______ molecules

nonpolar

Monosaccharides are ________ molecules

polar

describe the structure and major functions of the plasma cytoskeleton

Structure: Composed of protein filaments, including microfilaments, intermediate filaments, and microtubules Function: Structural support of cell; cell movement and contraction

describe the structure and major functions of the rough endoplasmic reticulum

Structure: Continuous with the nuclear envelope; flattened sacs dotted with ribosomes Function: Protein synthesis and post translational processing

which of the following molecules is not component of a phospholipid? a) cholesterol b) glycerol c) phosphate d) fatty acid

A

the chemical that tags protein for destruction in a cell is called_____

ubiquitin

There are five main classes of lipids: triglycerides, ketones, phospholipids, eicosanoids, and steroids. All ______ are based on the structure of cholesterol. a) triglycerides b) ketones c) phospholipids d) eiosanoids e) steroids

E

describe the structure and major functions of the golgi apparatus

Structure: Series of flattened sacs near the endoplasmic reticulum Function: Post-translation processing; packaging and sorting of proteins

describe the structure and major functions of the peroxisomes

Structure: Similar in appearance to lysosomes, but smaller Function: Breakdown of toxic substances, including hydrogen peroxide

describe the structure and major functions of the nucleus

Structure: Surrounded by double-layered nuclear envelope Function: Houses the DNA, which dictates cellular function and protein synthesis

how genetic information is passed on to daughter cells during mitosis

a copy of every chromosome is created; thus, following division, a complete set of chromosomes is found in the nucleus of each new cell.

what is the function of actin filaments

also termed F-actin or microfilaments. Actin filaments are polymers of actin monomers (G-actin). Actin filaments form the core of thin filaments in muscle cells.

give a brief description of lipids functions in cells

an energy reserve, regulate hormones, transmit nerve impulses, cushion vital organs, and transport fat-soluble nutrients

describe the role of transmembrane proteins in the transport of molecules across the plasma membrane

are specific and selective for the molecules they move, and they often use energy to catalyze passage. Also, these proteins transport some nutrients against the concentration gradient, which requires additional energy.

give a brief description of carbohydrates functions in cells

carbohydrates are molecules that contain carbon, hydrogen and oxygen in specific ratios, they are broken down into glucose and used to produce ATP through cellular respiration

Know the general characteristics of the four major classes of biomolecules

carbohydrates, proteins, lipids and nucleic acids

describe the role of transfer RNA in protein synthesis

carry amino acids to the ribosomes during protein synthesis

The precursor molecule for all steroids is _____

cholesterol

briefly describe tight junctions and where they are found

commonly found in epithelial tissue that is specialized for molecular transport. intergral membrane proteins called occluding fuse adjacent cells together to form a nearly impermeable barrier to the movement of substances between cells

the proteins that form gap junctions between two adjacent cells are called _____

connexions

division of the cytoplasm into two daughter cells during cell division is called _____

cytokinesis

list the four types of chemical interactions responsible for tertiary protein structure in the order of their strength of bonding

hydrophobic interactions, hydrogen bonds, salt bridges, and sulfur-sulfur covalent bonds.

Transmembrane protein are examples of _____ membrane proteins

integral

the first section of a polypeptide to be translated is called the _____; it is important in directing the translated protein to its final destination

leader sequence

what are the three types of filaments found in the cytoskeleton? Name a special function of each type of filament

microtubules, actin filaments, and intermediate filaments.

are triglycerides generally polar or nonpolar

non-polar

name two specialized structures that phospholipids can form in an aqueous environment.

phospholipid bilayer and micelle

which physiological functions are associated phospholipid bilayer

the bilayer has a hydrophobic core that prevents the passage of polar molecules while allowing the relatively free diffusion of non-polar molecules. This is important because it allows the bilayer to select which molecules it will allow into and out of the cell.

what is the name of the first part of a polypeptide chain that is translated from mRNA? What is it function?

the first step of the initiation stage is the binding of a specific initiator methanol tRNA and the mRNA to the small ribosomal subunit. The large ribosomal subunit then joins the complex, forming a functional ribosome on which elongation of the polypeptide chain proceeds.

describe the role of anticodons in protein synthesis

these are found on the molecules of tRNA and their function is to base pair with the codon on a strand of mRNA during translation. This action ensures that the correct amino acid will be added to the growing polypeptide chain. A tRNA molecule will enter the ribosome bound to an amino acid.

to initiate transcription of DNA, the enzyme RNA polymerase binds to the a) initiator codon b) termination codon c) centromere d) leader sequence

C

during which phase of mitosis do the chromosome pairs move to opposite poles of the cell? a) prophase b) metaphase c) anaphase d) telophase e) pro metaphase

C

During which phase of mitosis is the mitotic spindle developing? a) prophase b) metaphase c) anaphase d) telophase e) pro metaphase

A

Glycogen and lipids are stored a) as inclusions in the cytosol b) in storage vesicles c) in secretory vesicles d) in lyosomes e) in the nucleolus

A

Two mature cells of different types (like an epithelial cell and a muscle cell) would contain _______. (Please ignore egg and sperm cells in thinking about this question). a) basically the same genes, and therefore the same set of proteins b) basically the same genes, some of the same proteins, but some different proteins c) basically the same genes, but entirely different sets of proteins d) entirely different set of genes, and therefore entirely different sets of proteins

B

Which cytoskeletal component gives cells much of their structure and support, and also forms spindle fibers? a) microfilaments b) microtubules c) intermediate filaments

B

Which of the following biomolecules is not a polymer? a) Polysaccharide b) Phospholipid c) Protein d) Nucleic acid

B

hydrogen bonding between the amino hydrogen of one amino acid and the carboxyl oxygen of another amino acid in a protein is responsible for a) primary protein structure b) secondary protein structure c) tertiary protein structure d) quaternary protein structure

B

the base sequence on tRNA that recognizes the mRNA codon by the law of complementary base pairing is called the a) tRNA codon b) anticodon c) amino codon d) leader codon e) initiator codon

B

which cell-to-cell adhesion allows quick transmission of electrical signals between adjacent cells? a) desmosome b) gap junction c) tight junction d) all of the above

B

What is a lagging strand? a) a sequence of nucleotides in DNA that binds RNA polymerase b) a sequence of amino acids at the beginning of a polypeptide that directs the polypeptide to it destination c) the newly synthesized DNA strand formed by ligation of Okazaki fragments d) the proteins filaments that extend between two cells to form desmosomes e) the protein filaments that form cilia

C

Which cell component is a site of protein production, a site of calcium storage, and a site of lipid synthesis? a) nucleus b) Golgi apparatus c) endoplasmic reticulum d) lysosomes

C

A fatty acid that has two double bonds between carbon atoms is called a) a saturated fatty acid b) a desaturated fatty acid c) a monounsaturated fatty acid d) a polyunsaturated fatty acid e) an eicosanoid

D

during replication, which enzyme causes DNA to uncoil? a) DNA polymerase b) RNA polymerase c) DNA kinase d) helicase e) DNA ligase

D

for proteins to be synthesized in association with the rough endoplasmic reticulum, the leader sequence must bind to a ______ on the membrane of the endoplasmic reticulum. a) transport vesicle b) secretory vesicle c) coated vesicle d) signal recognition protein e) promoter

D

which of the following nucleic acids is not a pyrimidine? a) cytosine b)thymine c) uracil d) adenine

D

which organelle produces most of a cell's ATP? a) nucleus b) peroxisome c) Golgi apparatus d) mitochondrion e) Smooth endoplasmic reticulum

D

define replication, how does replication differ from transcription

DNA replication is the process of making two daughter strand where each daughter strand contains half of the original DNA double helix. Transcription is the process of synthesis of RNA using DNA as a template.

explain how genetic information is stored in DNA

Genetic information is stored in the sequence of bases along a nucleic acid chain. The bases have an additional special property: they form specific pairs with one another that are stabilized by hydrogen bonds. The base pairing results in the formation of a double helix, a helical structure consisting of two strands.

where is the genetic information of a cell stored? which type of molecule stores this type of information?

Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA), DNA molecules

give a brief description of nucleic acid functions in cells

Nucleic acids are the main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

give a brief description of proteins functions in cells

Proteins are responsible for nearly every task of cellular life, including cell shape and inner organization, product manufacture and waste cleanup, and routine maintenance. Proteins also receive signals from outside the cell and mobilize intracellular response.

describe the function of RNA polymerase in transcription

RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence, during the process of transcription.

describe the structure and major functions of the smooth endoplasmic reticulum

Structure: Continuous with rough endoplasmic reticulum; tubular structure without ribosomes Function: Lipid synthesis and post-translation procession of proteins; transport of molecules from endoplasmic reticulum to Golgi apparatus; calcium storage

describe the structure and major functions of the ribosomes

Structure: Granular organelles composed of proteins and rRNA; located in cytosol or on surface of rough endoplasmic reticulum Function: Translation of mRNA to synthesize proteins

describe the structure and major functions of the lysosomes

Structure: Granular, saclike; scattered throughout the cytoplasm Function: Breakdown of cellular and extracellular debris

describe the structure and major functions of the plasma membrane

Structure: Lipid bilayer with scattered proteins and cholesterol molecules Function: Maintains boundary of cell and integrity of cell structure; embedded proteins serve multiple functions

describe the structure and major functions of the mitochondria

Structure: Oval-shaped, with an outer membrane and an inner membrane with folds called cristae that project into the matrix Function: ATP Synthesis

describe the role of rough endoplasmic reticulum in protein synthesis

The endoplasmic reticulum presents a large surface area on which these ribosomes can be situated, therefore allowing protein synthesis to occur on a large scale. Rough ER is responsible for transporting the newly synthesized proteins to the Golgi apparatus.

Describe the basic structure of the plasma membrane.

The plasma membrane is composed of a phospholipid bilayer, which is two layers of phospholipids back-to-back. Phospholipids are lipids with a phosphate group attached to them. The phospholipids have one head and two tails. The head is polar and hydrophilic, or water-loving.

define transcription and translation and describe the role of DNA in protein synthesis

The synthesis of proteins occurs in two sequential steps: Transcription and Translation. Transcription occurs in the cell nucleus and uses the base sequence of DNA to produce mRNA. The mRNA carries the message for making a specific protein out to the cytoplasm where translation occurs.

what is the function of intermediate filaments

Their functions are primarily mechanical and, as a class, intermediate filaments are less dynamic than actin filaments or microtubules. Intermediate filaments commonly work in tandem with microtubules, providing strength and support for the fragile tubulin structures.

name the 5 stages of mitosis

These phases are prophase, pro metaphase, metaphase, anaphase, and telophase.

describe the role of messenger RNA in protein synthesis

They carry the coding sequences fro protein synthesis and are called transcripts; they form the core of a cell's ribosomes (where protein synthesis takes place)

describe the role of ribosomes in protein synthesis

This is the site where protein synthesis takes place. The rRNA molecules direct the catalytic steps of protein synthesis--the stitching together of amino acids to make a protein molecule.

define transcription and translation and describe the role of genes in protein synthesis

Together, transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene's DNA is passed to a similar molecule called RNA (ribonucleic acid) in the cell nucleus.

define transcription, where does it occur in the cell

Transcription takes place in the nucleus. It uses DNA as a template to make an RNA molecule. RNA then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs. Translation reads the genetic code in mRNA and makes a protein.

define translation, where does it occur in the cell

Translation takes place in ribosomes, and is the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis.

the mRNA codon that is transcribed from the DNA triplet ATC is _____

UAG

the membrane of the smooth endoplasmic reticulum is continuous with the membrane of the Golgi apparatus

false

briefly describe gap junctions and where they are found

found in a variety of tissue types, most notable for their presence in smooth muscle and in the muscle of the heart, they allow the muscle to contract as a unit.

briefly describe desmosomes and where they are found

found in tissues subject to mechanical stress, such as those in the heart, uterus and skin. They are a filamentous junction between two adjacent cells that provides strength so that the cells do not tear apart when the tissue is subjected to stress

which physiological functions are associated with micelle

functions as a transport for nonpolar molecule in an aqueous environment

a section of DNA that codes for a specific protein is called a _____

gene

are carbohydrates generally polar or nonpolar?

generally polar

what is the function of microtubules

they provide the rigid, organized components of the cytoskeleton that give shape to many cells, and they are major components of cilia and flagella (cellular locomotory projections). They participate in the formation of the spindle during cell division (mitosis).

describe the role of genetic code in protein synthesis

this can be described as the identification of each group of three nucleotides and its particular amino acid. The sequence of these triplet groups in the mRNA dictates the sequence of the amino acids in the protein.

More than one codon may code for a single amino acid

true

According to the law of complementary base pairing, in RNA, adenine base pairs with _____

uracil

name the four functions of membrane proteins

•Enzymatic functions: All enzymes are a type of protein. • Transportation: Membrane proteins can allow hydrophilic molecules to pass through the cell membrane. •Signal transduction. Some membrane proteins can feature a binding site. • Cell recognition. •Intercellular joining. •Attachment.