Chapter 4

describe telophase

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

Stages of mitosis

-1st stage; at this stage, the nuclear envelope dissappears -2nd stage; at this stage, there are two very distinct poles of the cell -3rd stage; at this stage, a cleavage furrow is evident -4th stage, at this stage, the nuclear envelope reappears

Purines

-Adenine -Guanine

Pryrimidines

-Cytosine -Thymine -Uracil

Steps in interphase (which is before the mitotic phase)

-G1 (first gap phase) -S (synthesis phase) -G2 (second gap phase)

Steps in the mitotic Phase

-Prophase -Metaphase -Anaphase -Telophase -cytokinesis

differences between RNA and DNA

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

true statements regarding an intron

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

mRNA

-binds to the small subunit of the ribosome -carries the genetic code to the ribosome

describe a codon

-complementary to an anticodon -a three base sequence of mRNA -code for an amino acid to stop

during translation, mRNA

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

these are nucleic acids

-dna -rna

describe ribosomes

-each ribosome is composed of several enzymes and ribosomal RNA (rRNA) molecules -each ribosome has three pockets that serve as binding sites for tRNA (A,P, and E sites) -they are found in the cytosol and on the outside of the rough ER and nuclear envelope -Each ribosome consists of a small and a large subunit in their inactive form that come together only when translating mRNA

translation occurs in 3 steps

-elongation -initiation -replication

tRNA

-has a section that binds to a codon -bound to an amino acid -binds to the large subunit of the ribosome

diploid cells

-liver cell -23 homologous pairs -somatic cell -skin cell -2n

DNA

-may contain thymine -double helix -the longest chain of nucleotides -contains deoxyribose

why is cancer more common in the elderly? select all that apply

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

haploid cells

-sperm cell -1n -egg cell -gamete -germ cell

describe G0 phase

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

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

cells divide when:

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

the events of protein synthesis

1) a template strand of DNA contains base triplets 2) codons of mRNA are transcribed from DNA triplets 3) anticodons of tRNA bind to the mRNA codons 4) amino acids are linked into a peptide chain

the sequence of events during protein processing and secretion

1) protein formed by ribosomes on RER 2) protein packaged into transport vesicles, which bud from ER 3) transport vesicles unload protein into golgi complex 4) golgi complex modifies protein structure 5) secretory vesicles release protein by exocytosis

steps of translation

1) ribosome binds mRNA 2) a tRNA antocodon 3) a new amino acid 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

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

1. Initiator tRNA 2. Methionine 3. mRNA 4. Start codon AUG 5. Ribosomal subunits

Which of the following DNA sequences is complementary to 5' TAGAC 3'?

5' GTCTA 3'

According to the law of complementary base pairing, which of the following statements about double-stranded DNA is TRUE?

A = T and C = G A + G = C + T

Someone with ____________ would be considered heterozygous for the "D" trait.

Dd

The complementary mRNA strand synthesized from the DNA sequence of CTGAC would be __________.

GACUG

Which of the following DNA molecules is the most stable?

GCGTGCAC CGCACGTG

Which of the following statements is false about genes?

Once a gene is turned on, it is activated in all cells.

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

RNA polymerase

Which of the following would prohibit cell division?

The cell is crowded in by neighboring cells.

How does DNA influence the synthesis of lipids, carbohydrates, and steroids?

The proteins that DNA codes for catalyze the reactions that synthesize these compounds.

What happens when a stop codon is encountered in the mRNA?

The ribosomal complex falls apart and the protein is released into the cell.

Someone can be ____________ if they possess the genotype but not the phenotype.

a carrier

Transcription occurs when __________.

a messenger RNA molecule is synthesized from DNA in the nucleus

Hemophilia is caused by a sex-linked recessive allele. This means that __________.

a son who has hemophilia inherited the allele from his mother

alternative forms of a gene are known as ___________

alleles

describe a cleavage furrow

an indentation between the future cells that forms as cytokinesis progresses

digestive enzymes

are secreted by exocytosis

kinases, ATPases

are used in the cytosol as metabolic enzymes

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

Which of the following events does NOT occur in prophase of mitosis?

chromosomes are replicated

the division of cytoplasm to form two cells is called ______

cytokinesis

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

some hormone receptors

delivered to the plasma membrane

the genetic code in _______ specifies which type of _________ a cell can make

deoxyribonucleic acid (DNA); proteins

in humans, any cell with 23 pairs of chromosomes is said to be _________. sperm and egg cells, however, are _________, meaning they contain only 23 unpaired chromosomes

diploid; haploid

transcription is the process of copying genetic instructions from _________ to _________

dna;rna

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

enzymes encoded by genes synthesize these products

A codon of tRNA is complementary to an anticodon of mRNA.

false

As helicase unwinds the DNA molecule, the separated strands are kept apart by DNA polymerase.

false

Centromeres divide during metaphase.

false

In translation, the initial tRNA is in the A site of the ribosome.

false

Personality traits, such as sex drive and aggression, are not influenced by DNA.

false

The three base sequence on the transfer RNA is the codon.

false

A segment of DNA that codes for the production of a molecule of RNA is known as a(n) __________.

gene

Which of the following occurs as the ribosome shifts down the mRNA by a distance of three nucleotides?

he tRNA that was in the P site moves into the E site

he enzyme __________ unzips and unwinds the DNA molecule.

helicase

In chromatin, DNA winds around disc-shaped clusters of eight proteins called ________.

histones

one member of each _________ pair of chromosomes is inherited from the individual's mother and one from the father

homologous

GG would describe someone otherwise known as ______________________

homozygous dominant

The Human Genome Project is responsible for all of the of the following advancements except __________.

identifying the chromosomal locations of every disease-producing mutation

In familial hypercholesterolemia, individuals with two abnormal alleles die of heart attacks in childhood, those with only one abnormal allele typically die as young adults, and those with two normal alleles have normal life expectancies. This exemplifies __________.

incomplete dominance

mendelian genetics

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

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

Genomic medicine

it studies the entire DNA endowment of an individual and how it influences health and disease

molecular genetics

it uses the techniques of biochemistry to study DNA structure and function

cytogenetics

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

a ___________ is a chart that organizes chromosomes in order by size and other physical features

karyotype

The mitotic spindle fibers attach to chromosomes via special structures called __________

kinetochores.

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

locus

UV radiation can cause changes to the DNA sequence known as __________.

mutations

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

nucleotides

The amino acids carried by the tRNA are eventually joined to one another by ________ bonds.

peptide

Neglecting the alleles that someone has in their genome, ____________ refers to whether or not a gene is expressed.

phenotype

Which of the following represents the structure of a nucleotide?

phosphate-sugar-base

Eye color is caused by genes at multiple loci. This phenomenon is called __________.

polygenic inheritence

a cluster of several ribosomes reading one mRNA during translation is called a _____________

polyribosomes

rough endoplasmic reticulum

proteins are synthesized by ribosomes bound to it, it packages proteins into clathrin coated transport vesicles

Translation is the synthesis of __________.

proteins from mRNA

A version of a trait that requires a homozygous genotype for expression is called a __________.

recessive allele

histones, RNA polymerase

return to the nucleus for cellular metabolism

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

ribosomes

You were able to radioactively tag and thereby trace an amino acid that is used to make insulin, a hormone that will be exported out of the cell. The pathway of the tagged amino acid would be __________.

rough ER ---> golgi complex ---> golgi vesicle --> extracellular fluid.

DNA replication is said to be __________.

semi-conservative

each daughter DNA consists of one new strand (synthesized from free nucleotides) and one old strand (conversed from the parental DNA). this process is called __________ replication

semiconservative

describe the location of the anticodon

tRNA

Translation occurs when _________

the blueprint of the RNA molecule is used to bind amino acids together to form proteins

Which of the following statements about DNA replication is TRUE?

the leading strand is replicated continuously, while the lagging strand is replicated discontinuously

Homozygous is the term describing a situation where someone has ____________ alleles.

the same

Which of the following statements about microtubules during anaphase is TRUE?

those attached to chromosomes shorten, while those that are unattached elongate

DNA replication results in two identical daughter molecules each consisting of one old (original) strand and one newly-synthesized strand.

true

Doubled-stranded DNA consists of two antiparallel strands, meaning that one strand is oriented in the 5' to 3' direction, while the other is oriented in the 3' to 5' direction.

true

The DNA replication machinery is assembled at the replication fork.

true

The anticodon is the three base sequence on the messenger RNA that binds with the codons of the transfer RNA.

true

The point where separation of the DNA occurs is called the replication fork.

true