Sexual Reproduction Flashcards
1
Q
Sexual Reproduction
A
- Involves 2 key processes
- Formation of haploid cells/sex cells/gametes
- Contains genetic info form parents
- 2 sex cells fertilize to create zygote (first cell in organism)
2
Q
Types of gametes
A
Father produces sperm cells= male gametes
Mother Produces egg cell= female gametes
3
Q
Types of fertilization
A
- External: release gametes into water
- Fusion: gametes fuse
- Pollination: insects pollinate flower
- Internal: exchange sperm, ferizle egg
4
Q
Meiosis
A
- How haploid gametes are formed
- The way sex cells are reproduced are similar for all organisms
- Has two stages similar to mitosis
- In meiosis chromosomes split from 46 to 23 unlike mitosis
5
Q
N
A
n=haploid
2N= diploid
Sex cells in humans only have 23 n
6
Q
Genetic variation
A
- combination of two gametes (sperm and egg) will result in a complete set of chromosomes (diploid, 2n = 46)
- homologous chromosomes= complete set of DNA from each parent (one version of each gene)
- ensures the offspring is genetically unique from each parents
7
Q
Production of Sex Cells
A
- Metois l, metois ll
- Diploid parent cell (46) → mitosis l → 2 haploid cell (23) → mitosis ll → 4 haploid cells (23)
8
Q
Formation of sex cells
A
- Gametogenesis
- two types of gametogenesis in humans
- Formation of sperm by spermatogenesis
- Formation of egg cells or ova by oogenesis
- Both are produced through a process called meiosis
9
Q
Interphase
A
- Cell grows to nearly twice in size (G1, G2)
- Nucleus makes a copy of its DNA (s)
- Organelles are also replicated (G2)
10
Q
Meiosis I: Prophase I
A
- Chromatin condenses into chromosomes
- The nuclear membrane dissolves
- Centrioles move to opposite sides of the cell
- Spindle fibers begin to grow
11
Q
Tetrad
A
- Homologous chromosomes come together and intertwine to form a tetrad by a process called synapsis
- Chromosome is made up of 2 sister chromatids, 1 chromosome from each parent
- 4 sister chromatids come together to form tetrad
12
Q
Crossing over
A
- intertwined chromatids from different chromosomes break off and reattach at the chiasmata
- chiasmata= parts where chromosome are intertwined
- Creates an exchange of genetic material at certain sections
- Mixes genetic information creates genetic variety
13
Q
Meiosis I: Metaphase I
A
- tetrads migrate towards the equatorial plate
- Spindle fibers attach at centromeres
tetrads align their centromeres at the middle of the cell
14
Q
Meiosis I: Anaphase I
A
- Homologous chromosomes move to opposite poles of the cell when the spindle fibers shorten
- one of the two chromosomes from each homologous pair will be in each new daughter cell and therefore are genetically unique
15
Q
Meiosis I: Telophase I
A
- nuclear membranes reform, spindle fibers dissolve and the cell begins to divide via the first cycle of cytokinesis (cleavage furrow)
- Each new cell has only 1, not two, duplicated copy of a chromosome
- cells are haploid (Only the maternal or paternal chromosome is in each new cell)
