Quiz 3 Flashcards
Progeny - offspring
All life, from pro to euk, must leave behind progeny
Cell division takes place within multicellular organisms on a regular basis
Cell theory
All cells come from pre-existing cells
Cells are the basic unit of life
Smallest unit that exhibits all emergent properties of life
Cancer (uncontrolled growth and division) and apoptosis (programmed cell death) are the exception to controlled division/growth of cells
Growth and development of new daughter cells must occur in interphase
Interphase can encompass 50-90% of the cell cycle
Most cells are in interphase
Interphase
G meant gap earlier, not growth, gap before the cells divide and synthesis
G1: cell grows in size and accumulates enzymes for DNA replication
Growth and normal metabolic roles
Chemical signaling, production of mRNA
S (DNA Synthesis): exact replication of chromosomes (DNA)
DNA replication
G1 to S is a major point
At S, has twice the DNA, needs to prepare proteins and such to hold that DNA
G2: cell generates new organelles, accumulates nutrients, and prepares for cell division
Growth and preparation for mitosis
M (mitosis or meiosis):
Mitosis: cell’s duplicated chromosomes (sister chromatids) can be separated and moved to opposite poles in the parent cell
Occuring at the same time, cytokinesis: cytoplasmic movement in which a new cell membrane is formed between two new emerging cells, and two distinct but genetically identical daughter cells are created
In contrast, most brain cells may exist in interphase Gsub0 with no probability of mitosis or cell division
Karyokinesis: Prophase, metaphase, anaphase
Cytokinesis: Telophase
Happens during cell division
Locus (loci): the position on a chromosome where a gene resides
Genes lie along the linear chromosome
Genes lie along the linear chromosome
Made of nucleotides
Chromosome in a sister chromatid are identical
When cells are in the process of cell division - chromosomes are condensed
Count chromosomes by counting number of centromeres
Sister chromatids vs homologous chromosomes Homologous chromosomes (exist before S in Interphase) have the same genes along their length, but the version of each gene might be different Sister chromatids have exactly the same genes and exact version of the genes along their length
Stages of mitosis
All somatic cells (body cells) are generated through mitotic cell division
In animals - diploid (2n) - meaning they have chromosomes in pairs (one from each parent)
The sister chromatids are not identical in a diploid
The cleavage furrow signifies cytokinesis, and first appears during telophase
Gametes (eggs and sperm), came from germ cells in humans
Haploid (n)- have only one copy of each chromosome, generated through meiosis
Asexual reproduction
One cell makes an exact copy of itself
Prophase
Initially, nuclear envelope holds chromatin fibers, which are uncondensed chromosomes
Sister chromatids produced in the S phase condense into coils
Now visible under a light microscope, can be used for karyotyping
Each pair of chromatids is attached at their centromere (seen as a little indentation)
Chromosomes condense, centrosomes radiate microtubules and migrate to opposite poles
Microtubules begin to take an important role (prometaphase?)
Metaphase
Attached sister chromatids migrate to equator of parent cell
This is the official start of metaphase
Chromosome align in the center of the cell
Spindle fibers (made up of microtubules) pull on the sister chromosome until they break apart at the centromere
Spindle fibers connects to the kinetochore
End
Marked by the break and movement of chromatids towards their poles
Anaphase
Movement of chromatids in opp directions up until they reach opp poles
Shortest phase in mitosis
Upon separation the chromatids now taken on chromosome status
Once we see the break, we are in Anaphase
Sister chromatids become individual chromosomes when the centromere splits
Telophase
Reverses the process seen in prophase
Spindle apparatus breaks down, nuclear envelope reforms around the chromosomes, which then begin to uncoil into chromatids and return to interphase states
Generation of complete daughter cells is almost finished
Opposite of prophase/prometaphase
Start of the split of the cytoplasm
Cytokinesis
Usually occurs simultaneously with telophase
Cell membranes reform between the two new cells
Completes separation and therefore mitosis
Animals vs plant mitosis
Animal: cleavage furrow during cytokinesis which pinched inward on the parent cell until it separates in two
Plant: in contrast, use a cell plate, which extends from the center of the metaphase plate outward across the cell
