Reproduction

• Mitosis involves only one parent. the offspring have identical genes to the parent - so there’s no variation between parent and offspring
• what can mitosis be used for?


  Cell growth, repair, cloning and asexual reproduction.
• Mitosis is when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes
• Mitosis:

  A diploid cell duplicates, the chromosomes line up, the spindle pulls the identical strands apart, the cytoplasm splits

  
• Meiosis:

  A diploid cells chromosomes are copied, chromosomes with the same genes and similar sequences pair up and swap some DNA, the pairs divide creating 4 unique haploid cells

  
• 1= bladder

  2= glands

  3= penis

  4=urethra

  5= sperm duct

  6= testes

  7= scrotum

  
• 1= fallopian tube/oviduct

  2= ovary

  3= cervix

  4= uterus

  5= vagina

  
• In meiosis the daughter cells are unique and have 23 chromosomes each. It is used to make sex cells (gametes)
• (male) Urethra - contains urine or semen
• Glands - produce fluid which combines with sperm to make semen
• The penis ejaculates sperm into the vagina during sexual intercourse
• Foreskin - protects the tip of the penis
• Sperm duct - (aka vas deferens) connects testes with the urethra
• Testis - make and store sperm
• Scrotum - bag of skin allowing the testes to hang outside the body, keeping the sperm cells cool
• Oviduct/ fallopian tube - where fertilisation occurs, ciliates cells help push the egg along, caries the ovum from ovary to uterus
• Uterus - where the embryo implants and develops
• Cervix - ring of muscle
• Bladder - stores urine
• (female) Urethra - urine leaves through
• Vagina - where penis is placed during sexual intercourse
• Ovary - contains sex hormones and egg cells that can mature each month
• erectile tissue - swells when filled with blood to make the penis errect
• endometrium - lining of uterus, has a good blood supply for implantation of an embryo
• hormones:

  female = oetrogen

  male = testosterone

  these trigger secondary sexual characteristics
• ova - female gametes

  sperm - male gametes
• the menstrual cycle lasts for 28 days:

  • day 1-4 = menstruation starts, uterus lining breaks down
  • day 4-14 = uterus lining builds up into a thick, spongy layer full of blood vessels, ready to receive a fertilised egg
  • day 14 = ovulation, an egg develops and is released from the ovary
  • day 14-28 = the wall is maintained, waiting for a fertilised egg, then starts to brak down again
• FSH - follicle stimulating hormone

  • produced in the pituitary gland
  • causes an egg to mature in one of the ovaries
  • stimulates ovaries to produce oestrogen
  • oestrogen the prevents the release of FSH
• oestrogen:

  • produced in ovaries
  • stimulates the release of LH
• LH - luteinising hormone:

  • produced by pituitary gland
  • stimulates release of an egg on day 14
• progesterone:

  • produced in the ovaries after ovulation
  • maintains the lining of the uterus during second half of the cycle. when progesterone levels fall, the lining breaks down
  • prevents release of FSH and LH
• Placenta - lets the blood of the embryo and mother get very close to allow the exchange of food, oxygen and waste (urea and carbon dioxide) by diffusion
• amniotic sac - surrounds the embryo and is full of amniotic fluid, protecting the embryo against bumps
• During the first week of development, the zygote moves through the Fallopian tube towards the uterus where it implants itself into the endometrium (lining).
• if pregnancy occurs progesterone continues to be produced from the follicle
• at week 12 of pregnancy an embryo becomes a foetus
• During the first week of development, the zygote moves through the Fallopian tube towards the uterus where it implants itself into the endometrium (lining).
• stamen contains:

  • anther - contains pollen (male gametes)
  • filament - stalk that supports the anther
• carpel contains:

  • stigma - pollen grains stick to
  • style - supports the stigma
  • ovary - contains ovules (female gametes)
• pollination - the transfer of pollen from an anther to a stigma so the male gamete can fertilize the female gamete in sexual reproduction