4.2 Asexual Reproduction Flashcards
(20 cards)
Asexual reproduction
production of offspring without using sex cells
Asexual reproduction is commonly used by…
- Unicellular organisms
- Plants & fungi
- Aquatic and terrestrial invertebrates
Plant runners
horizontal stems that grow from a plant’s base that can form new plants
Hydra produce offspring by what
outgrowths of their bodies, called “budding”
Female aphids produce only female aphids
they are already pregnant when born
Fungi can reproduce through fragmentation
is when a piece breaks off and becomes independent
Cell division
- Cells (eukaryotic) divide during mitosis (nuclear division) and cytokinesis (cytoplasmic division)
- Cell division produces two daughter cells that are genetically identical to each other and the parent cell
How many chromosomes in a human
In your somatic (body) cells, you have 46 chromosomes.
That is 23 pairs of chromosomes. One chromosome in each pair is from each of your biological parents.
What’s a chromosome
Chromosomes are bodies of DNA, tightly wound together
Mitosis
During regular cell division, each chromosome duplicates
The sister chromatids (copies of the chromosome) are joined by a centromere
0 - Interphase
- Genetic material in the form of thread like chromatin duplicates
- This results in the pairs of sister chromatids.
1 - Prophase
- Chromatin shortens and thickens to be visible under a microscope
- Centrioles separate and move to the poles
- Nuclear membrane starts to dissolve
2 - Metaphase
- Spindle fibers form
- Chromosomes move to a line
3 - Anaphase
- Sister chromatids divide (split at centromere) and move to opposite sides
- If mitosis proceeds correctly, the same number of chromosomes will be found at each pole of the cell
4 - Telophase
- Chromosomes reach opposite poles of the cell and begin to disappear (go back to being chromatin)
- Spindle fibers disappear
- Nuclear membrane starts to reform
- Two identical daughter cells are now present
Cytokinesis
- The cell divides its cytoplasm and organelles into two new daughter cells
- In many cells (protists, fungi & animal cells) a furrow develops
- In plant cells, a cell plate appears on the equator. This becomes the cell wall
Biotechnology
The field of biology that involves the use of living things in engineering, industry and medicine
Plant Cloning
In 1958, carrot plants were first cloned in labs
Cells are placed in a growth medium, which allows them to grow into small plants
Plants are identical
Animal Cloning
1996, Dolly was the first mammal to be cloned from an adult body cell.
The process involved substituting the desired nucleus in place of the original nucleus
Why do we clone?
- Mass production of livestock and crop plants
- Cloning genetically modified organisms (GMOs) Table 1
- Cloning endangered species
