Reproduction and Inheritance
Types of reproduction
Asexual reproduction is where the cells divide by mitosis. This only involves one parent and so
there is no genetic variation. Asexual reproduction leads to genetically identical offspring, called
clones. Most cells in the body reproduce asexually through mitosis and is common in small
animals and plants.
Mitosis: 1) Cells grow bigger and increase in mass. DNA replicates and sub-cellular structures
and organelles also replicate.
2) One set of chromosomes is pulled to each end of the dividing cell and the nucleus
divides.
3) The cytoplasm and cell membrane also divide to form two genetically identical
daughter cells
Sexual reproduction involves gametes (male and female sex cells) fusing to form a zygote,
which develops into a baby. The formation of gametes is in a type of cell division called meiosis.
Offspring from sexual reproduction inherit genetic information from both parents, introducing
variation. Sexual reproduction is risky as it relies on two sex cells meeting and fusing.
Meiosis: 1) The genetic information of a cell is copied so there are 4 sets of each chromosome.
Each chromosome forms a chromatid.
2) The cell then divides twice to form four gametes, each with a single set of
chromosomes.
Male sex cells = sperm. Female sex cell = egg. Each sex cell has a single set of chromosomes,
and when two sex cells meet, the single new cell has a full set of chromosomes, one from each
parent. Each sex cell has 23 chromosomes and joins to form a child with 46 chromosomes.
Reproduction in fungi, plants and malaria parasites
Malaria parasites:
1) A female mosquito takes its first blood meal from someone infected with malaria and absorbs
the infected gametes.
2) Sexual reproduction with the gametes in the mosquito in the midgut occurs.
3) Malaria parasites are injected into the blood of a non-infected human in the second
bloodmeal through the mosquito's saliva and travel to the liver.
4) The hepatic cell containing the parasite asexually reproduce along with infected red blood
cells, forming infected gametes – cycle continues
Fungi:
1) Mycelium (the furry mold on the fungi) grows
2) If two mycelia meet, the cytoplasm of the mycelia fuse together.
3) The nuclei fuse between the mycelia (the mycelia become temporarily diploid).
4) Meiosis occurs and spores are produced (become haploid again)
Types of reproduction
Asexual reproduction is where the cells divide by mitosis. This only involves one parent and so
there is no genetic variation. Asexual reproduction leads to genetically identical offspring, called
clones. Most cells in the body reproduce asexually through mitosis and is common in small
animals and plants.
Mitosis: 1) Cells grow bigger and increase in mass. DNA replicates and sub-cellular structures
and organelles also replicate.
2) One set of chromosomes is pulled to each end of the dividing cell and the nucleus
divides.
3) The cytoplasm and cell membrane also divide to form two genetically identical
daughter cells
Sexual reproduction involves gametes (male and female sex cells) fusing to form a zygote,
which develops into a baby. The formation of gametes is in a type of cell division called meiosis.
Offspring from sexual reproduction inherit genetic information from both parents, introducing
variation. Sexual reproduction is risky as it relies on two sex cells meeting and fusing.
Meiosis: 1) The genetic information of a cell is copied so there are 4 sets of each chromosome.
Each chromosome forms a chromatid.
2) The cell then divides twice to form four gametes, each with a single set of
chromosomes.
Male sex cells = sperm. Female sex cell = egg. Each sex cell has a single set of chromosomes,
and when two sex cells meet, the single new cell has a full set of chromosomes, one from each
parent. Each sex cell has 23 chromosomes and joins to form a child with 46 chromosomes.
Reproduction in fungi, plants and malaria parasites
Malaria parasites:
1) A female mosquito takes its first blood meal from someone infected with malaria and absorbs
the infected gametes.
2) Sexual reproduction with the gametes in the mosquito in the midgut occurs.
3) Malaria parasites are injected into the blood of a non-infected human in the second
bloodmeal through the mosquito's saliva and travel to the liver.
4) The hepatic cell containing the parasite asexually reproduce along with infected red blood
cells, forming infected gametes – cycle continues
Fungi:
1) Mycelium (the furry mold on the fungi) grows
2) If two mycelia meet, the cytoplasm of the mycelia fuse together.
3) The nuclei fuse between the mycelia (the mycelia become temporarily diploid).
4) Meiosis occurs and spores are produced (become haploid again)
