Chapter 11 Flashcards
What makes Eukaryotic cell Reproductive signals different from prokaryotic ones?
1.Eukaryotic cells do not constantly divide whenever condition are adequate. 2. need to benefit entire organism 3. Some cells become specialized and no longer divide
Cytokinesis
division of cytoplasm and cell separation
Sister Chromatids
newly replicated chromosomes closely associated with each other
Mitosis
process that segregates newly replicated chromosomes into two new nuclei
Cell Cycle
period from one cell division to the next
3 Broad stages of the cell cycle
Interphase, Mitosis, Cytokinesis
Interphase
Nucleus is visible, typical cell functions occur
G1 Phase
between cytokinesis and S phase, cell prepares to replicate
S Phase
DNA is replicated, sister chromatids remain together
G0 Phase
Inactive resting phase, cell enters if not preparing for division
Restriction point (G1-S phase transition)
commitment to DNA replication and subsequent cell division
G2 phase:
Cell prepares for Mitosis
What are the phases of interphase
G1, S, and G2
Photophosyrlation
addition of a phosphate group
Kinase
Enzyme that catalyzes transfer of a phosphate group from ATP to a target protein
Cyclin-Dependent Kinases (CDKs)
control progress through the cell cycle
Cyclin
allosterically regulates CDKs
How does Cyclin regulate CDK’s?
by binding to CDK, and exposing it’s active site, turning it on
Cell Cycle checkpoints
regulate progress through the cell cycle by checking to see if everything is in order
G1 Checkpoint Trigger
DNA damage
S Checkpoint trigger
incomplete DNA replication or DNA damage
G2 Checkpoint trigger
DNA damage
M Checkpoint trigger
chromosomes unattached to spindle
RB protein
inhibits the cell cycle, unless it is phosphorylated by cyclin-CDK, in which case it no longer blocks the cell
Growth Factors
proteins that allow for cell division
Nucleosomes
Histones
proteins with positive charges that attract negative phosphate groups of DNA and pack them
Nucleosomes
beadlike units formed by the interaction of histones and DNA, 10:1 compaction
Chromatin
DNA molecules bound to proteins, 50:1 compaction
Cohesins
proteins that hold sister chromatids together during G2
Centromere
attachment site of sister chromatids, as well as spindle fibers
Condensins
Coat DNA molecules to make them more compact
What happens in Prometaphase (mitosis)
nuclear envelope breaks down, chromosomes attach to spindle
What happens in Prophase (mitosis)
DNA condenses into chromosomes, spindles assemble
What happens in Metaphase (mitosis)
Chromosomes align on equatorial plate
What happens in Anaphase (mitosis)
Chromosomes migrate to opposite poles
Centrosome
organelle located near the nucleus that organizes microtubules
Spindle Apparatus
made of microtubules, move sister chromatids apart
What happens in Telophase (mitosis)
Chromosomes decondense, two new nuclei form
Kinetochore
structure found on each chromatid, important for chromosome movement
Polar Microtubules
form framework of
spindle and run from one
pole to another
Kinetochore microtubules
attach to kinetochores and to microtubules in opposite halves of spindle
How does the Metaphase Checkpoint work? (Mitosis)
the APC is inhibited if a spindle isn’t properly attached, stopping mitosis
APC (anaphase promoting complex)
activates separase, which hydrolyzes cohesion
Daughter Chromosomes
Separated Chromatids
Asexual reproduction
offspring are identical to their single parent
Sexual Reproduction
offspring receive genetic material from both parents
Gamete
sex cell created via meiosis (sperm and egg cells in humans)
Somatic cells
cells not specialized for reproduction
Homologous pairs
matching pairs of chromosomes that carry same sequence of genes for same traits
Haploid
cell with one set of chromosomes
Diploid
cell with two sets of chromosomes
Zygote
cell created from fused gametes (fertilized egg)
Meiosis
cell division process by which a mature individual produces sex cells
What happens in Meiosis I
Homologous chromosome pairs separate, but the individual chromosomes (sister chromatids) stay together
What happens in Prophase I
Chromatin condenses
What happens in Prometaphase I
Crossing over
What happens in Metphase I
Homologous pairs line up on
equatorial (metaphase) plate
What happens in Anaphase I
The paired homologous chromosomes (each with two chromatids) move toward opposite poles
What happens in Telophase I
chromosomes gather into nuclei, cell divides
Synapsis
specific parallel alignment (pairing) of
homologous chromosomes
Tetrad
four chromatids of each
pair of homologous
chromosomes
Chiasmata
regions of attachment that form between nonsister chromatids
Crossing over
exchange of
genetic material between
nonsister chromatids at the
chiasmata
Recombinant chromatids
result of crossing over, increases genetic variety
Independent Assortment
chromosome pairs align randomly
during metaphase I
What happens in Meiosis II
sister chromatids separate, final product 4 haploid daughter cells
What happens in Prophase II
chromosomes condense again
What happens in Metaphase II
Centromeres of paired
chromatids line up along
equatorial plate of each cell
What happens in Telophase II
Chromosomes gather into nuclei, cells divide again
What happens in Anaphase II
Chromatids separate, becoming chromosomes, and move to opposite poles
Aneuploidy
chromosomes lacking or present
in excess
Translocation
a piece of a chromosome may break away and attach to another chromosome
Karyotype
number, shapes, and sizes of all chromosomes of a
cell
Polyploid
organisms with complete extra sets of chromosomes
Necrosis
cell is starved of oxygen and nutrients (unintentional)
Apoptosis
programmed cell death (intentional)
