A&P Chapter 4- Genetics and Cellular Function (Saladin)

During translation, mRNA:

-carries the genetic code from the nucleus to the cytoplasm -contains a cap that acts like a passport, permitting it to pass through a nuclear pore and tells a ribosome where to begin translation

Describe telophase.

-chromatids cluster on each side of the cell -a nuclear envelope reappears

Name the enzyme that synthesizes molecules of RNA complementary to the DNA sequence during transcription.

RNA polymerase

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

S Phase

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

cytokinesis

Cells stop ______ when they snugly contact neighboring cells (contact inhibition) or when nutrients or growth factors are withdrawn.

dividing

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

mitotic spindle

Genomics is the field of biology that deals with:

the study of the whole genome and how its genes and noncoding DNA interact to affect the structure and function of the whole organism

Sperm and egg cells, are said to be haploid because:

they contain only 23 unpaired chromosomes

The first tRNA to bind to a ribosome at the start of the process called ______ is the initiator tRNA.

translation

The structure of DNA is commonly described as a double helix that resembles a spiral staircase. Indicate which of the following statements are true regarding the DNA structure:

- 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

Indicate which of the following statements are true regarding an intron.

- an intron is a portion of mRNA that must be removed before translation - an intron is a portion of mRNA that does not code for protein

Indicate the differences between DNA and RNA.

-RNA is much smaller. DNA, by contrast, averages more than 100 million base pairs long. -RNA consists of only one nucleotide chain whereas DNA is a double helix. -RNA contains a sugar called ribose whereas DNA contains a sugar called deoxyribose

List the steps of translation in correct order.

-Ribosome bind mRNA -tRNA anticodon binds to complementary mRNA codon -New amino acid is linked to the growing peptide chain -tRNA released from ribosome, available to pick up another amino acid

Indicate which of the following are true regarding the cell cycle:

-Some cells leave the cell cycle for a "rest" and cease to divide for days, years, or the rest of one's life -Some cells like stomach and skin cells divide rapidly

Indicate which of the following is true with regard to recessive alleles.

-Their expression is masked in the presence of a dominant allele -They are expressed only when present on both of the homologous chromosomes

Indicate which of the following statements are true regarding the discovery of the double helix of DNA.

-Watson and Crick published their findings on the structure of the DNA without performing any experiments of their own -Rosalind Franklin's S-ray diffraction showed that the DNA is a helix

Indicate which of the following are components of nucleotides.

-a sugar -a phosphate group -a nitrogenous base

Indicate which of the following are true of the G0 phase of the cell cycle.

-an inability to stop cycling and G0 is characteristic of cancer cells -the duration of this phase is variable (for some cells it may last days, years, or the rest of one's life) -during this phase cells leave the cell cycle for a "rest" and cease to divide

Indicate which of the following events occur during prophase.

-centrioles are pushed apart -spindle fibers grow from the centrioles -chromosomes condense -nuclear envelope disappears

Indicate which of the following are true regarding the Human Genome Project (HGP) and its results.

-it showed that human worldwide are over 99.99% genetically identical -it demonstrated that Homo sapiens has fewer genes than previously believed -it increased our knowledge of disease-causing mutations -it was an international effort

After a protein is synthesized, it undergoes some structural modifications. Describe this process.

-the process is known as posttranslational modification -the protein may be folded and stabilized by disulfide bonds -carbohydrates may be added to the protein -it may involve removal of some amino acid segments

Describe chaperones.

-they aid a newly synthesized protein in folding to its proper shape -they help prevent improper associations between different proteins -they are also known as stress proteins or heat shock proteins

If the mother is a carrier for hemophilia (X-linked trait) but the father does not have this condition, what is the chance that their son will have the disease?

50%

Describe the composition of a nucleosome.

A DNA molecule wrapped around a spool of histones

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. One strand of DNA determines the base sequence of the other. This is the law of complementary base pairing. Adenine base pairs with thymine in DNA and with uracil in RNA. Cytosine always base pairs with guanine.

A normal karyotype of a human male consists of a total of 23 pairs of chromosomes, including 22 pairs of _______ and 1 pair of ______.

autosomes; sex chromosomes

A sequence of three DNA nucleotides that codes for one amino acid is called a:

base triplet

Mutations that destroy the protective function of tumor suppressor genes can lead to ______.

cancer

Susie is not color-blind, but she transmitted a color-blindness gene to her son. She is said to be a ______ of the color blindness gene.

carrier

Sister chromatids are joined together at a pinched spot called the ______.

centromere

When a cell is preparing to divide, it makes an exact copy of all its nuclear DNA. Each chromosome then consists of two parallel filaments called _______.

chromatids

DNA does not exist as a naked double helix in the nucleus of a cell, but is complexed with proteins to form a fine filamentous material called ______.

chromatin

Match the nitrogenous bases with their classification.

cytosine and thymine- Pyrimidines (molecules with a single carbon-nitrogen ring) adenine and guanine- Purines (molecules with two carbon-nitrogen rings)

Mendelian Genetics

deals with parent-offspring and larger family relationships to discern and predict patterns of inheritance within a family lnie

The genetic code in ______ specifies which type of ______ a cell can make.

deoxyribonucleic acid (DNA); proteins

If a protein is going to be used in the cytosol, it is likely to be made by ______. However, if it is going to be secreted from the cell, it is made by ______ on the RER.

free ribosomes; polyribosomes

During a cell's life cycle, G1, S, and G2 make up the phase collectively known as ______.

interphase

The X and Y chromosomes, which determine the gender of an individual are known as the ______ chromosomes.

sex

All the cells that are not germ cells (egg and sperm cells or their precursors) are called ______ cells.

somatic

During the process of translation, the three-nucleotide sequence (AUG) serves as a code for methionine and also as a ______ codon that signals the beginning of a new protein. The three nucleotide sequences (UAG, UGA or UAA) terminate the process and are called ______ codons.

start; stop

______ is the last step of translation. A stop codon is reached and the A site binds a release factor which causes the newly-synthesized polypeptide to be released form the ribosome.

termination

Describe the events that occur 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

Describe the events that occur 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

During protein synthesis, the step using DNA to make mRNA is called ______, and the step in which mRNA is "read" to make protein is called ______.

transcription; translation

Cytogenetics

uses the techniques of cytology and microscopy to study chromosomes and their relationship to hereditary traits

Which of the following are nucleic acids:

-DNA -RNA

Indicate functions of mitosis.

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

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

-a chaperone may guide the protein in folding into the proper shape -the Golgi complex may modify the protein by adding carbohydrate chains -enzymes in the ER may modify the protein through posttranslational modification

Brown eye color requires:

-genes for the enzymes that synthesize the pigment melanin -phenylalanine, from which the melanin is made

Indicate which of the following are involved in the initiation of translation.

-methionine -start codon AUG -mRNA -ribosomal subunits -initiator tRNA

Cells divide when:

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

Humans are estimated to have 20,000 to 25,000 genes that constitute about ____% of the DNA. The other ____% is noncoding DNA, which plays various roles in chromosome structure and regulation of gene activity, some of which may have no function at all.

2; 98

Describe a cleavage furrow.

An indentation between the future cells that forms as cytokinesis progresses

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

False

True or False: Dominant alleles are more common in the gene pool than recessive alleles.

False

True or False: The coding portion of DNA contains genes that constitute about 98% of the DNA.

False. 98% of the DNA consists of noncoding DNA that contains no genes. Noncoding DNA plays various roles in regulation of gene activity, and some of that noncoding DNA has no specific function (it is known as "junk DNA").

A Punnett square is used to:

Show the expected outcome of a single mating

True or False: Different codons can code for the same amino acid.

True. Sometimes two or more codons represent the same amino acid.

Chromosomes ______ and ______ are called sex chromosomes because they determine the individual's sex; all others are called autosomes.

X; Y

There are three steps in translation: initiation, elongation, and termination. What is elongated in the second stage?

a polypeptide

When a cell replicates its nucleus and then pinches in two to form two new daughter cells it is said to be in M phase otherwise known as the ______ phase.

mitotic

In a molecule of DNA, the nitrogenous bases ____ and ____ form two hydrogen bonds with each other.

adenine; thymine. Remember that in a molecule of DNA, adenine and thymine form two hydrogen bonds with each other, while guanine and cytosine form three.

Alternative forms of a gene are known as ______.

alleles

Sister chromatids are joined together at a pinched spot called the ______ containing, on each side, a protein plaque called a ______.

centromere; kinetochore

An individual with type AB blood has both blood type alleles IA and IB, and therefore expresses both A and B proteins on the surface of their erythrocytes. This occurs because the alleles are ______>

codominant

During DNA replication, the enzyme DNA ______ opens up a short segment of the helix, exposing its nitrogenous bases.

helicase

Proteins which serve as "spools" to help organize chromatin are called ______.

histones

When a red flower crossed with a white flower produces a pink flower, which of the following is demonstrated?

incomplete dominance

When three or more allelic forms exist for the same gene it is known as ______.

multiple alleles

Any change in 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

Chromatin appears divided into segments called ______ consisting of a core particle (a spool of eight ______ with DNA around them) and a short segment of linker DNA leading to the next core particle.

nucleosomes; histones

______ cause cell division to accelerate out of control, sometimes by inducing the excessive secretion of growth factors that stimulate mitosis, or the production of excessive growth-factor receptors.

oncogenes

Alkaptonuria is an example of ______, a phenomenon in which one gene can have many phenotypic effects.

pleiotropy

Eye color and skin color are traits determined by genes at multiple loci. They are examples of ______.

polygenic inheritance

Proteins that need to be used in the cytosol (i.e. the enzymes of glycolysis) are generally synthesized by free ______ in the cytosol.

ribosomes

Describe the accuracy of DNA replication.

the few errors made by DNA polymerase are usually corrected by DNA polymerase or other repair enzymes

Translation occurs in three steps. Name these steps.

-initiation -elongation -termination

Cancer is more common in the elderly because:

-mutations accumulate over time -the DNA and tissue repair mechanisms are less efficient as we age

List the steps of mitosis in the correct order.

-prophase -metaphase -anaphase -telophase

List two characteristics of genes.

-some genes overlap each other, so some segments of DNA belong to two different genes -some genes produce only RNA molecules and not proteins

Transcription is the process of copying genetic instructions from ______ to ______.

DNA; RNA

Describe anaphase.

Daughter chromosomes migrate to opposite ends of the cell

After proteins are synthesized, some remain in the cell and some are secreted. Match the proteins with their destination and function.

Digestive enzymes- secreted by exocytosis Some hormone receptors- delivered to the plasma membrane Kinases, ATPases- used in the cytosol as metabolic enzymes Histones, RNA polymerase- returned to the nucleus for cellular metabolism

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

Enzymes encoded by genes synthesize these products

When synthesized proteins are to be exported out of the cells (i.e. digestive enzymes), they can be packaged into secretory vesicles that fuse with the plasma membrane and are released through exocytosis. The secretory vesicles originate in what organelle?

Golgi complex

Golgi complex

It modifies proteins, often by adding carbohydrate chains. It packages some proteins into lysosomes and some into secretory vesicles that are secreted through exocytosis.

rough endoplasmic reticulum

Proteins are synthesized by ribosomes bound to it. It packages proteins into clathrin coated transport vesicles.

One strand of a molecule of DNA has the sequence: ACGTGA. The nucleotide sequence of the complementary strand would be ______. Give your answer as a sequence of base pairs.

TGCACT

Johnny received a gene for type A blood from his mother and a gene for type B blood from his father. These tow gene variants are called ______.

alleles

The X and Y chromosomes, which determine the gender of an individual are known as the ______ chromosomes.

allosome

During translation, the role of transfer RNA (tRNA) is to bind a free _____ in the cytosol and deliver it to the ribosome to be added to a growing protein chain.

amino acid

The role of tRNA during translation is to deliver ______ to the ribosome for protein synthesis.

amino acids

A(n) ______ is a 3-base sequence found in tRNA.

anticodon

Chromosomes X and Y are called sex chromosomes because they determine the sex of an individual; all the others are called ______.

autosomes

Chromosomes that do not determine the sex of an individual are called:

autosomes

______ occurs as a long-thin strand of DNA-protein complex, found in a loosely packed formation, while ______ are formed by a tighter packing, via coiling and compact folding of the DNA-protein complex and are thus visible.

chromatin; chromosomes

A three-base sequence of mRNA is called a ______.

codon

deoxyribonucleic acid (DNA)

contains a sugar called deoxyribose; contains nitrogenous bases A, T, C, G; it consists of two nucleotide chains (double helix); it functions in the nucleus; it codes for synthesis of RNA and protein

ribonucleic acid (RNA)

contains a sugar called ribose; contains nitrogenous bases A, U, C, G; consists of one nucleotide chain; functions mainly in the cytoplasm; carries out the instructions in DNA

RNAs interpret the code in DNA and use those instructions to synthesize proteins. RNA works mainly in the ______, while DNA remains in the ______.

cytoplasm; nucleus

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

gene

When a woman gives birth, prolactin stimulates her mammary glands to produce casein, a protein that her body has never synthesized before. This demonstrates that:

genes can be turned on or off

All the coding and non coding DNA found in the haploid number of chromosomes from one organism is known as the ______.

genome

The transmission of genetic characteristics from parent to offspring is called:

heredity

An individual with different alleles at a loci on homologous chromosomes is said to be ______ for that trait.

heterozygous

Cells contain chromosomes inherited from the individual's father and mother. The two copies of chromosome 4 for example are called ______ since they are the same size, shape and code for the same information.

homologous chromosomes

DNA ligase

joins the newly synthesized segments of DNA

During DNA replication, the new short segments of DNA in one of the strands are joined together by DNA ______.

ligase

The location of a particular gene on a chromosome is called its ______.

locus

The main role of ______ during translation is to carry the genetic code from the nucleus to the cytoplasm.

mRNA

RNA directly involved in producing proteins are ribosomal RNA, ______ RNA (mRNA), and ______ RNA (tRNA).

messenger; transfer

The ______ bases in DNA are adenine, cytosine, guanine and thymine.

nitrogenous

DNA is a polymer of ______, each of which consists of a phosphate, a sugar, and a single or double-ringed nitrogenous base.

nucleotides

Describe the location of an anticodon.

on tRNA

DNA helicase

opens the DNA helix, exposing the nitrogenous bases

_______ is a term that means the percentage of a population with a given genotype that actually exhibits the predicted phenotype.

penetrance

The observable traits of an individual that result from his/her genes are called the ______, whereas the ______ refers to the combination of alleles present for a gene.

phenotype; genotype

One mRNA can have several ribosomes attached to it at one time during translation of mRNA. This cluster of ribosomes is called ______.

polyribosome

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

pores

DNA polymerase

reads about 100 nitrogenous bases per second and matches them with complementary free nucleotides

Name 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.

replication

______ are the organelles that process coded genetic messages and assemble amino acids into proteins specified by the code.

ribosomes

When a protein must be exported outside the cell, it is synthesized in ribosomes bound to the ______. Then it is modified and packaged into a _______.

rough endoplasmic reticulum; transport vesicle

Each daughter DNA consists of one new strand (synthesized from free nucleotides) and one old strand (conserved from the parental DNA). This process is called ______ replication.

semiconservative

Conversion of nucleotide sequences into amino acid sequences is known as ______.

translation

Molecular Genetics

uses the techniques of biochemistry to study DNA structure and function