Asexual and Sexual life cycles Flashcards
Pros/cons of asexual reproduction
Pros: no need for a mate, less energy required, poorly adapted individuals are removed from the population, low “genetic load”
Cons: less diversity, trouble if environment changes
Pros/Cons of sexual reproduction
Pros: greater genetic variability bc of 2 parents
Cons: specialized cells are energetically expensive, you may need to find/compete for a mate
What processes are common to all sexual life cycles?
Meiosis and fertilization
Genome
All of the DNA in a cell
What are chromosomes composed of?
DNA and protein
How are pairs of chromosomes similar/different?
Similar: They have the same genes
Different: They have different alleles
Polyploid
More than 2 copies of each chromosome are made
Why are plants more likely to be polyploid?
Proportionally, they have access to more energy
Aneuploid?
Different number of copies of each chromosome
How many homologous pairs do humans have?
23
What type of environment do asexual organisms tend to live in?
Static environment
Which organisms reproduce asexually?
ALL prokaryotes, some eukaryotes
How are haploid and diploid cells made in sexual reproduction?
Diploids become haploids in meiosis. haploids become diploids during fertilization
What do plants use meiosis for?
to make spores
What type of reproduction do asexual organisms use/dont use?
Dont use: Meiosis/fertilization
May use: Mitosis, binary fission
What MUST be involved for sexual reproduction?
Union of haploid cells to form a zygote. Meiosis and fertilization
Sister chromatids
Joined copies of an original, duplicated chromosome
Centromere
a region of repetitive sequences of DNA where a chromatid is most closely attached to its sister chromatid
What happens to sister chromatids as they separate?
They become known as individual chromosomes after they separate
Binary fission
An form asexual reproduction used by single celled organisms resulting in 2 daughter cells
- Origin of replication is copied and both origins move to opposite ends of the cell
- Replication continues, each origin is at the opposite end of the cell, the cell elongates
- Replication finishes and the middle of the plasma membrane pinches inward
When does crossing over take place?
Prophase 1 of meiosis
What is the result of meiosis 1?
Two haploid cells
Homologous chomosomes
Two chromosomes of a pair that have the same length, centromere position and staining pattern. Both chromosomes carry genes controlling the same characteristics
Which organisms can perform meiosis?
Those with a nucleus(eukaryotes)
