BOTANY LAB: MITOSIS Flashcards
An orderly series of events where cells divide
CELL CYCLE
It has two divisions:
1. Interphase
2. Mitosis
CELL CYCLE
Process of division that produces two daughter cells with identical chromosomal content of parent cell.
MITOSIS
- A period in which chromosomes are not visible with light microscope
- The living cells are not dividing
INTERPHASE
It has 3 intervals:
1. G1 phase
2. S phase
3. G2 phase
INTERPHASE
3 INTERVALS OF INTERPHASE
- Lengthy period after the nucleus divides; RNA and ribosomes are produced, and cells increase in size
G1 PHASE (growth or gap one)
3 INTERVALS OF INTERPHASE
- DNA replication takes place
S PHSE (synthesis)
3 INTERVALS OF INTERPHASE
- Where mitochondria and other organelles divide; microtubules are produced; coiling and condensation of chromosomes begin
G2 PHASE (growth or gap two)
- Where one cell divides into two and each of the two cells to produce two or more daughter cells
- The daughter cells have the exact number
Location: Meristem (found in roots and stem tips)
MITOSIS
Normally comes with mitosis; division of the remainder of the cells
CYTOKINESIS
STAGES OF MITOSIS
- The first and longest stage of mitosis
PROPHASE
STAGES OF MITOSIS
THE MAIN FEATURE OF THIS STAGE
- 2 chromosomes become shorter and thicker; 2 strands are apparent (CHROMATIDS)
- Nuclear envelop dissociated; nucleolus disintegrates
PROPHASE
STAGES OF MITOSIS
A band formed from microtubules and microfilaments inside the plasma membrane
PRE-PROPHASE
Holds each pair of chromatids together (short, thick, and rod like)
CENTROMERES
A dense region composed of protein complex found on the outer surface of each centromere
KINETOCHORE
Help distinguish certain chromosomes from others in a nucleus; knob like appearance
SATELLITE
Developed extend in arcs between two invisible poles located towards the end of the cell
SPINDLE FIBERS
Keg-shaped structure; Found on fungi and algae and animal cells located outside the nucleus with radiating asters (Starlike rays)
CENTRIOLES
STAGES OF MITOSIS
THE MAIN FEATURE OF THIS STAGE
- Alignment of the chromosomes in the circle midway between the 2 poles around the spindle and in the same plane as the Pre-prophase band
METAPHASE
STAGES OF MITOSIS
THE MAIN FEATURE OF THIS STAGE
- Chromosomes become aligned; centromere are in the center of the cell
METAPHASE
STAGES OF MITOSIS
THE MAIN FEATURE OF THIS STAGE
- Equator an invisible circular plate (similar to earths equator)
METAPHASE
STAGES OF MITOSIS
- Chromosomes condense and become visible
- Spindle fibers emerge from the chromosomes
- Nuclear envelope breaks down
- Centrosomes move toward opposite poles
PROPHASE
STAGES OF MITOSIS
- Chromosomes continue to condense
- Kinetochores appear at the centromeres
- Mitotic spindle microtubules attach to kinetochores
PROMETAPHASE
STAGES OF MITOSIS
- Chromosomes are lined up at the met a phase plate
- Each sister chromatic is attached to a spindle fiber originating from opposite poles
METAPHASE
STAGES OF MITOSIS
- Centromere split in two
- Sister chromatids (now called chromosomes are pulled toward opposite poles)
- Certain spindle fibers begin to elongate the cell
ANAPHASE
STAGES OF MITOSIS
- Chromosomes arrive at opposite poles and begin to decondense
- Nuclear envelope material surrounds each set of chromosomes
- The mitotic spindle breaks down
- Spindle fibers continue to push poles apart
TELOPHASE
STAGES OF MITOSIS
- The shortest phase
ANAPHASE
STAGES OF MITOSIS
- Sister chromatids of each chromosome separate and move to opposite poles which are now the daughter chromosomes
- Movement may be due to shortening of spindle fibers
ANAPHASE
STAGES OF MITOSIS
THE MAIN FEATURE OF THIS STAGE
- Each group of daughter chromosomes are surrounded by a reformed nuclear envelop
- Daughter chromosomes become longer and thinner
- Nucleoli reappear
- Spindle 2 fibers disintegrate
- Cell plates are formed
TELOPHASE
STAGES OF MITOSIS
- Shorter keg-shaped fibrils (microfibrils) develop in the equator between the daughter nuclei called PHRAGMOPLAST
TELOPHASE
A hollow structure of dictyosome derived vesicle fused together
CELL PLATE
Shared by two daughters cells
MIDDLE LAMELLA
Minute strands of protoplasm that extend via tiny desmotubules through the walls between cells
PLASMODESMATA
The division of cytoplasm to form two new cells, overlaps with the final stages
CYTOKINESIS
Cell plate forms down the middle of the cell, splitting it into two daughter cells separated by a new wall
CYTOKINESIS
The form of cell division in which a cell divides into four daughter cells each of which has half of the number of chromosomes of the original cells
MEIOSIS
- The cells return to having the normal (called ‘diploid’) number of chromosomes after fertilization of the ova by the sperm
- It occurs prior to the formation of sperm (in males) and ova (in females)
MEIOSIS
STAGES OF MEIOSIS
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
STAGES OF MEIOSIS
- The chromosomes condense, and the nuclear envelope breaks down; crossing over occurs
PROPHASE I
STAGES OF MEIOSIS
- Pairs of homologous chromosomes move to the equator of the cell
METAPHASE I
STAGES OF MEIOSIS
- Homologous chromosomes move to opposite poles of the cell
ANAPHASE I
STAGES OF MEIOSIS
- Chromosomes gather at the poles of the cells. The cytoplasm divides
TELOPHASE I and CYTOKINESIS
STAGES OF MEIOSIS
- A new simple forms around the chromosomes
PROPHASE II
STAGES OF MEIOSIS
- Chromosomes line up at the equator
METAPHASE II
STAGES OF MEIOSIS
- Centromeres divides; chromatids move ti opposite poles of the cell
ANAPHASE II
STAGES OF MEIOSIS
- A nuclear envelope forms around each set of chromosomes. The cytoplasm divides
TELOPHASE II and CYTOKINESIS
Those the make up skin, hair, and muscle are duplicated by mitosis
SOMATIC CELLS
Somatic cells are __________ - meaning they have two copies of each chromosomes
DIPLOID
Are produced by meiosis in special tissues of male testes and female ovaries
SPERM and OVA
