SB1c-d Flashcards
What are specialised cells?
Cells that have a specific function.
What are human gametes?
The egg cell and sperm cell.
What is the difference between diploid and haploid cells?
Diploid cells have two sets of chromosomes and haploid cells only have one.
What does an egg cell consist of? (4)
- Cell membrane
- Cytoplasm
- Jelly coat
- Haploid nucleus
What do the cell membrane, cytoplasm and jelly coat do?
Cell membrane: Fuses with the sperm cell membrane. Becomes hard after fertilisation to stop other sperm cells entering.
Cytoplasm: Packed with nutrients. Supply fertilised egg cell with energy and raw materials for growth and development of the embryo.
Jelly coat: Protects the egg cell. Also hardens after fertilisation, to ensure that only one sperm cell enters the egg cell.
What does a sperm cell consist of? (6)
- Acrosome
- Mitochondria
- Tail
- Nucleus
- Cell surface membrane
- Streamlined shape
Explain the functions of the acrosome, mitochondria and tail in a sperm cell?
Acrosome: Is a small vacuole in the tip of the head. Contains enzymes that break down substances in the egg cell’s jelly coat. This allows the sperm cell to burrow inside.
Mitochondria: A large number of mitochondria are arranged in a spiral around the top of the tail, to release lots of energy to power the tail.
Tail: Waves from side to side to allow the sperm cell to swim.
Where does fertilisation occur?
In the oviducts.
How are egg cells transported?
By cells in the lining of the oviduct. They are adapted for this function by having hair-like cilia.
What are cilia?
An adaptation of the oviduct lining cells. They are covered in cell membrane and contain strands of a substance that can contract and cause wavy movement, to sweep substances along.
What are cells that line structures in the body called?
Epithelial cells. These cells with cilia are called ciliated epithelial cells.
What can we use to make bacteria show more in a microscope?
Stains.
What are bacteria cells?
Bacteria are prokaryotic, meaning their cells do not have nuclei or chromosomes. Instead, the cytoplasm contains one large loop of chromosomal DNA.
What does chromosomal DNA do?
Controls most of the cell’s activities.
What are plasmids?
Smaller loops of DNA. Plasmid DNA controls a few of the cell’s activities.
What are two things prokaryotic cells don’t have?
Mitochondria and chloroplasts.
What do bacteria consist of usually? (7)
- Flagellum
- Slime coat
- Flexible cell wall
- Cell membrane
- Cytoplasm
- Plasmids
- Chromosomal DNA
Explain the functions of the flagellum, slime coat, flexible cell wall and cytoplasm.
Flagellum: Used for movement. Is not covered in membrane and not all bacteria have them. Some have many flagella.
Slime coat: For protection - not all bacteria have this.
Flexible cell wall: For support - not made out of cellulose.
Cytoplasm: Contains ribosomes.
