Asexual Reproduction (lesson two) Flashcards
when does asexual reproduction occur?
This almost always occurs via cell division or mitosis
what is asexual reproduction?
Asexual reproduction is a form of reproduction in which a new individual is produced from a single parent by cell division
advantage to asexual reproduction
- Parent organisms do not have to seek out a mate
- Specialized mating behaviours are not required
- No specialized anatomy is required
Budding
A new individual develops from an outgrowth on the body of an organism
In what way does Hydra reproduce?
- Hydra reproduces the budding way
what happens to Hydra when the conditions are favourable
- When the conditions are favourable the hydra grows one or more extensions on the side of their bodies
- When they are large enough, these buds detach and live as a new genetically identical individual
what is fragmentation
Fragmentation is a process in which a piece or body fragment of the parent organism develops into a mature individual
what way does fungi develop?
all fungi develop the fragmentation way
how does fragmentation in fungi work?
Mushrooms grow small pieces, called spores, which break off and then develop into a new genetically identical mushroom
Growth stage
- Also known as Interphase
- Most of the cell’s life is spent in this stage
- 3 parts - G1, S, G2
what are the three parts of the growth stage?
- G1 phase is a cell growth phase
- S phase is DNA replication/synthesis
- G2 phase is another cell growth phase
Interphase
- Cell grows to nearly twice in size
- Nucleus makes a copy of its DNA
- Organelles are also replicated
Division stage
- A much shorter stage
- Two Parts:
1. Mitosis: Division of the Nucleus
2. Cytokinesis: Division of the Cytoplasm
Prophase
- Chromatin (DNA) condenses into chromosomes
- Centrioles move to opposite ends of the cell
- Spindle fibers form from the centrioles
- Nuclear membrane dissolves
Metaphase
- Spindle fibres attach to centromeres
- Chromosomes align along the equatorial plate
- Equatorial plate is like the equator of the cell
Anaphase
- Spindle fibres shorten
- Centromere splits and pulls chromatids to opposite ends of the cell
Telophase
- Chromosomes relax into chromatin
- Nuclear membrane reappears
-Two new nuclei are formed - Spindle fibres disappear
Is cytokinesis a part of mitosis?
cytokinesis is not a true part of mitosis
cytokinesis
- During cytokinesis, the cytoplasm divides
- In animal cells, cleavage furrows are formed.
- In plant cells, cell plates are formed
Mitotic spindles
spindle fibres
Kinetochore
protein over centromere that spindle fibres attach to
Kinetochore microtubule
spindle fibres attached to kinetochore
what happened on July 5th, 1996
On July 5th, 1996, the world’s most famous sheep, Dolly, was born
who created the first clone?
Dr. Ian Wilmut
cloning
- An adult body cell from the sheep he wished to clone and an unfertilized egg cell from another donor was obtained
- He then removed the nucleus from the egg cell and used an electric shock to fuse the adult body cell with the egg cell
- The egg then began to divide and develop normally after implanted into a third sheep’s uterus
how many attempts did it take to create dolly the sheep
277 attempts
do clones live long?
- clones still do not typically survive as long and commonly suffer from health complications
- Dolly died prematurely of lung disease common in older sheep and also displayed premature ageing (ex. Arthritis)
positives about cloning
- Use to reproduce endangered species when captive breeding is not enough
negatives about cloning
- It may result in genetically vulnerable species (i.e. more susceptible to diseases, mutations, etc.)
- Many people feel it is unnatural or unethical
