Dr Adrian Mascia REPRODUCTION IN HUMANS

Human Chromosomes

Each Human cell contains 46 chromosomes (2 pairs of the 23 types of chromosomes) There are 22 types of autosomal (body trait) chromosomes There are 1 pair of sex chromosomes (x or y) Somatic cells: Called Diploid Cells or 2N have two sets of chromosomes = 46 in total Humans have 23 homologous pairs of chromosomes in somatic cells = 44 chromosomes + XX (females) or +XY (males) THE HUMAN GENOME

Gametes (sex cells): Have 23 chromosomes Called Haploid cells or 1N Sperm = 22 chromosomes + X or Y Ova = 22 chromosomes + X THE HUMAN GENOME

ANIMAL MITOSIS

MITOSIS SLOWMATION

MITOSIS OVERVIEW BEGIN: One cell containing 4 single stranded chromosomes Interphase: Cell is in normal functioning state (replication of DNA material is occurring) Cell spends most of its time in this state Cannot see any chromosomes (unravelled) Prophase: Chromosomes begin to shorten and fatten (become visible) – true beginning of mitosis Centromere at centre of chromosome becomes visible Centrioles move apart, creating what is called a miotic spindle Metaphase: Miotic spindle is formed Double stranded chromosomes line up along equator of the cell (each strand of chromosome called a chromatid) Anaphase: Contraction of the miotic spindle, pulls toward the poles of the cells Each centromere divides so that a single strand of DNA goes to opposite sides of the cell (1 copy of each chromosome at each end of the cell) Telophase: Clear division in chromosomal positioning, chromosomes become thinner and less obvious Nuclear membrane or cell wall begins to form around each group of cells CYTOKINESIS: Process by which cell membrane or wall encloses, separating the genetic material, forming 2 cells

THE FEMALE REPRODUCTIVE SYSTEM COPYRIGHT PEARSON PRENTICE HALL Fallopian tube Ovary Uterus Urinary bladder Pubic bone Urethra Vagina Rectum Cervix

THE MENSTRUAL CYCLE COPYRIGHT PEARSON PRENTICE HALL The menstrual cycle is controlled by internal feedback mechanisms between the reproductive system and the endocrine system. The cycle takes an average of 28 days.

THE MENSTRUAL CYCLE COPYRIGHT PEARSON PRENTICE HALL Ovulation

REPRODUCTION HORMONES IN HUMANS HormoneProduced byFunction TestosteroneTesticlesMale sex traits FSHPituitaryStimulates egg/sperm dvlp Stimulate estrogen LHPituitaryStim. Testosterone Release of egg, corpus luteum, progesterone EstrogenOvariesFemale sex traits ProgesteroneCorpus luteumMaintains Uterus lining COPYRIGHT PEARSON PRENTICE HALL

Asexual vs. Sexual TYPES OF REPRODUCTION

PURPOSE OF REPRODUCTION To make sure a species can continue. Definition: Reproduction is the process by which an organism produces others of its same kind.

ASEXUAL REPRODUCTION A new organism (sometimes more than one) is produced from one organism. The offspring will have hereditary material uniform with the hereditary material of the parent organism. This means they will be genetically alike.

TYPES OF ASEXUAL REPRODUCTION Budding Regeneration Fission (Binary fission)

BUDDING Process by which a new, duplicate plant or animal begins to form at the side of the parent and enlarges until an individual is created. Very common in plants;

REGENERATION The ability to restore lost or damaged tissues, organs or limbs. It is a common feature in invertebrates, like worms and starfish.

FISSION Also called binary fission. Becoming two by division of the complete organism. A type of cell division.

SEXUAL REPRODUCTION Requires two sex cells – egg and sperm The egg and sperm join to form an entirely new organism Different from the parent organism

IMPORTANT! Asexual reproduction results in offspring that are genetically identical to the parent organism Sexual reproduction results in offspring that are genetically different from the parent organisms