Gametes + Cell Organisation Flashcards
Define “gametes”
Sex cells found in all organisms that reproduce sexually
What are the chromosomes of the gametes described as?
Haploid
When does the nucleus of gametes become diploid again?
At fertilisation when it becomes a zygote
List the structures in an ovum
- Haploid nucleus
- Lipid droplets
- Zona pellucida
- Cell membrane
- Lyosomes
- Cytoplasm
- Follice cells
How do egg cells move?
- They are incapable of independent movement
- Wafted along oviducts to the uterus
- By ciliated cells lining tubes and muscled contractions of the tubes
List all the structures of the sperm
- Haploid nucleus
- Acrosome
- Mitochondria
- Flagellum
What is the acrosome?
A type of lysosome containing digestive enzymes to digest zona pellucida
Why do sperm cells have many mitochondria?
- Carry out aerobic respiration
- To provide ATP
- To move flagellum
- Allows sperm to swim towards egg
What is the function of the flagellum?
Allows sperm to swim towards the egg cell
What happens in fertilisation?
- Sperm attracted to the ovum by chemicals released from it
- Once sperm makes contact with zona pellucida acrosome reaction takes place
- Acrosome in sperm head swells
- Fuses with sperm cell membrane
- Releases digestive enzymes from vesicles by exocytosis
- Breaks down zona pellucida
- Sperm head penetrates and fuses with egg cell membrane
- Egg cell releases chemicals by exocytosis from vesicles called cortical granules
- Into space between cell membrane with zona pellucida
- Triggers cortical reaction
- Makes ZP impenetrable to other sperm - only one fertilises it
- Sperm nucleus enters egg cell - tail discarded
- Sperm nucleus fuses with egg cell nucleus produces zygote
Define “tissue”
A group of specialised cells working together to carry out a particular function
Define “organ”
A group of tissues working together to carry out a particular function
Define “organ system”
A group of organs working together to carry out a particular function
Where does fertilisation take place?
Oviduct (Fallopian tube)
Define “fertilisation”
The fusion of haploid nuclei to form a diploid zygote
