Chapter 10/14 Flashcards
the repeating sequence of growth and division through which cells pass each generation
cell cycle
a protein complex that triggers anaphase; it initiates a series of reactions that ultimately degrades cohesion
anaphase-promoting complex (APC/C)
the complex of DNA and proteins of which eukaryotic chromosomes are composed; highly uncoiled and diffuse in interphase nuclei, condensing to form the visible chromosomes in prophase
chromatin
the vehicle by which hereditary information is physically transmitted from one generation to the next
chromosomes
a visible point of constriction on a chromosome that contains repeated DNA sequences that bind specific proteins - these proteins make up the kinetochore to which microtubules attach during cell division
centromere
any of a number of proteins that are produced in synchrony with the cell cycle and combine with certain protein kinases at certain points during cell division
cyclin
any of a group of protein kinase enzymes that control progress through the cell cycle - only active when complexed with cyclin
cyclin-dependent kinase (Cdk)
having two sets of chromosomes - in animals (twice the number characteristic gametes) in plants (the chromosome number characteristic of the sporophyte generation)
diploid (cell)
a haploid reproductive cell
gametes
the entire DNA sequence of an organism
genome
any of a number of proteins that bind to membrane receptors and initiate intracellular signaling systems that result in cell growth and division
growth factor
having only one set of chromosomes
haploid (cell)
refers to similar structures that have the same evolutionary origin - pair of same chromosome in diploid cell
homologous chromosomes
disk-shaped protein structure within the centromere to which the spindle fibers attach during mitosis
kinetochore
somatic cell division; nuclear division in which the duplicated chromosomes separate to form two genetically identical daughter nuclei
mitosis
a mutant form of a growth-regulating gene that is inappropriately “on” causing unrestrained cell growth and divison
oncogene
a normal cellular gene that can act as an oncogene when mutated
proto-oncogene
one of two identical copies of each chromosome, still linked at the centromere, produced as the chromosomes duplicate for mitotic division; similarly, one of two identical copies of each homologous chromosome present in a tetrad at meiosis.
sister chromatids
any of the cells of a multicellular organism except those that are destined to form gametes (germ-line cells)
somatic (cell)
a gene that normally functions to inhibit cell division; mutated forms can lead to the unrestrained cell division of cancer, but only when both copies of the gene are mutant
tumor-suppressor gene
a topoisomerase involved in DNA replication; it relieves the torsional strain caused by unwinding the DNA strands
DNA gyrase
a class of enzymes that all synthesize DNA from preexisting template
DNA polymerase
the enzyme responsible for formation of phosphodiester bonds between adjacent nucleotides in DNA
DNA ligase
the structure of DNA, in which two complementary polynucleotide strands coil around a common helical axia
double helix
the basic unit of heredity; a sequence of DNA nucleotides on a chromosome that encodes a protein, tRna, or rRNA molecule, or regulates the transcription of such a sequence
gene
any of a group of enzymes that unwind the two DNA strands in the double helix to facilitate DNA replication
helicase
the DNA strand that must be synthesized discontinuously because of the 5’-to-3’ directionally of DNA polymerase during replication, and the antiparallel nature of DNA
lagging strand
the DNA strand that can be synthesized continuously from the origin of replication
leading strand
a short segment of DNA produced by discontinuous replication elongating in the 5’-to-3’ direction away from the replication
okazaki fragment
the enzyme that synthesizes the RNA primers required by DNA polymerases
primase
the macromolecular assembly of enzymes involved in DNA replication; analogous to the ribosome in protein synthesis
replisome
the y-shaped end of a growing replication bubble in a DNA molecule undergoing replication
replication fork
in DNA replication, a sequence of about 10 RNA nucleotides complementary to unwound DNA that attaches at a replication fork
RNA primer
the phases of cell division during which the spindle breaks down, the nuclear envelope of each daughter cell forms, and the chromosomes uncoil and become diffuse
telophase
what is the difference between homologous chromosomes and sister chromatids?
Homologous chromosomes are made up of both maternal and paternal copies of the same chromosome, whereas sister chromatids in a single chromosome can be either a maternal or a paternal copy
list in order the eukaryotic cell cycle
(interphase)
-g1
-s
-g2
(m phase)
-mitosis
-cytokinesis
what events happen during interphase?
G1 (signal received - preparation to divide)
S (synthesize - DNA replication)
G2 (DNA proofreading)
describe the phases of mitosis.
- Prophase:
-chromosomes condense and become visible
-chromosomes appear as two sister chromatids held together at the centromere - Prometaphase:
-mitotic spindle attaches
- chromosomes attach to microtubules at the kinetochores - Metaphase:
- all chromosomes are aligned at equator of the cell, called metaphase plate
-chromosomes are attached to opposite poles - Anaphase:
-proteins holding centromeres for sister chromatids are degraded
- chromosomes are pulled to opposite poles - Telophase:
- nuclear envelopes re-form around chromosomes
-spindle is disassembled
what is the role of checkpoints in control of the cell cycle?
Cell cycle checkpoints are surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis.
what is the difference between proto-oncogene and tumor-suppressor genes?
the protein products of proto-oncogenes stimulate cell growth and division - they’re like a gas pedal in a car. Tumor suppressor genes, on the other hand, are in charge of negative regulation of the cell cycle, so their protein products stop its progression and promote apoptosis or cell death.
a complementary pair of nucleotide bases
base-pair
evaluate the significance of complementarity for DNA structure and function.
The two strands are held together by hydrogen bonds between the bases: adenine pairs with thymine and guanine pairs with cytosine. The two strands are thus complementary to each other
one strand of the parental duplex would remain intact in each daughter duplex; a new complementary strand would be synthesized with each parental strand - each daughter duplex would consist of one parental strand and one newly synthesized strand.
semiconservative model
what are the products of semiconservative replication?
Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.
describe the requirements for DNA replication.
replication requires three things: something to copy, something to do the copying, and the building blocks to make the copy.
the parental DNA molecules serve as a template, enzymes perform the actions of copying the template, and the building blocks are nucleotides.
explain why replication is discontinuous on one strand.
the nature of DNA mean that only one strand, the leading strand, can be synthesized continuously - the other strand, lagging strand, must be made in pieces, each with its own primer
diagram the function found at the replication fork
synthesize DNA, the double-stranded DNA is unwound by DNA helicases ahead of polymerases forming a replication fork containing two single-stranded templates
explain the function of telomeres.
protect the ends of chromosomes from nucleases and maintain the integrity of linear chromosomes
they protect us from cancer
what is the structure of DNA?
this will be a question on the test
-> double helix
-> antiparallel
