Chapter 7: The Cell Cycle and Cell Division Flashcards
Cells
basic components of life, self-contained biological processes
reproduction
Asexual Reproduction
super duper quick (think lightning or the flash)
really effective way of making new individuals
super popular
makes clones of the parent
only variation from mutation, so less variation
clones
genetically identical
dos Olivias salen
Mutations
alterations in the DNA caused by the environment or replication mistakes
Binary fission
used by most single-celled prokaryotes
means of reproduction
Mitosis
used by single-celled eukaryotes
produces fro genetically identical cells asexually
Sexual Reproduction
the fusion of two specialized cells called gametes
result in offspring with significant variation
uses meiosis
gamete
specialized cell
half of the genetic material as the parent cell
single set of chromosomes– one homolog from each pair
n chromosomes
haploid
Mesiosis
a process of cell division that results in daughter cells with only half of the genetic material of the original cell
random separation of genetic material so daughter cells are very different
differences lead to a better adapted organism lead to natural selection
Chromosome
a single molecule of DNA and associated proteins
somatic cells
body cells which are not specialized for reproduction
two sets of chromosomes in homologous pairs
homologous pairs
the pairs in which the two sets of chromosomes that somatic cells contain are organized into
have corresponding genetic information
zygote
the fused haploid gametes
diploid
2n chromosomes
fertilization
the fusing of two haploid gametes
Do all sexual life cycles involve meiosis?
yup
sometimes, just gamete then meiosis
some haploid becomes a haploid organism which eventually creates gametes
Haplontic organism sexual life cycle
protists, fungi, green algae
zygote is the only diploid cell in the life cycle
after formation, it immediately produces more haploid cells, generally spores (the dispersal units for the organism)
Alternation of generations
plants and fungi
meiosis creates haploid spores, they mitosis it up and produce a gametophyte
in flowering plants, there are super small (pollen and embryo sac)
in mosses, they are super big
gametophyte creates gametes by mitosis, which fuse to form the diploid zygote
the zygote mitosises it up and and creates a sporophyte
Diplontic organisms
animals, brown algae, fungi
gametes only haploid cells
mature or
What is the essence of sexual reproduction?
THE RANDOM SELECTION OF HALF OF THE DIPLOID CHROMOSOME SET to make a diploid
What needs to hPpen for cell division?
reproductive signal- initiates cell division and can come from inside or outside the cell
replication of DNA must occur
the DNA must be distributed to the two new cells
enzymes and organelles must be made and material needs to be added to the membrane
cytokinesis
the division of the cytoplasm
ori
the sort where replication of the circular chromosome started
The ORIgin of replication
ter
the site where replication ends
the TERminus of replication
True or false: In prokaryotes it is common to have 8 chromosomes
False, most prokaryotes have all of their genetic information on one chromosome
True or false: Most prokaryotes have circular chromosomes
true
Where does replication begin in Binary fission and what happens as it proceeds?
it begins near the center of the cell and as replication progresses the ori moves towards the ends of the cells
this process is driven by the binding of DNA to proteins that ensure its success
cytokinesis in binary fission
the actual division of a cell and contents
starts right after chromosome segregation
starts with a pinching in of the plasma membrane caused by the contraptions of fibers on the inside surface
as this pinching occurs, new cell wall materials are deposited, leaving two separate cells
Eukaryotic DNA replication
eukaryotes have like lots of chromosome, so each one follows a process akin to that in binary fission.
IN EUKARYOTES IT CAN ONLY OCCUR IN ONE STAGE IN THE CELL CYCLE
Eukaryotic DNA segregation
the chromosomes are all hanging out close together after replication and they must be separated so each daughter cell has a full lest after division
This is done by condensing them and pulling them to opposite ends of the cell
Cytokinesis in Eukaryotes
animals (just cell membrane) and plants (also cell wall) have different processes for cell division
Cell cycle
the period from one division to the next
eukaryotes- mitosis and cytokinesis (M phase)
and interphase
Interphase
the nucleus is visible typical cell stuff is happening
lasts from the end of cytokinesis to the start of mitosis
G1 S G2
G1
part of interphase gap 1 time varies, can last a ridiculously long time point of no return the cell is just being a regular cell
S
part of interphase
synthesis
DNA replication occurs here
G2
part of interphase
the cell is getting ready for mitosis (like making microtubulues and stuff like that)
gap 2
Mitosis
A SINGLE NUCLEUS GIVES RISE TO TWO DAUGHTER NUCLEI THAT EACH CONTAIN THE SAME NUMBER OF CHROMOSOMES AS THE PARENT NUCLEUS four phases Prophase Prometaphase Metaphase Anaphase Telophase