PSY 388 03 CHROMOSOMES INHERITANCE THE HUMAN CELL Every human being is made up of about 100 trillion cells Cell The smallest unit of life Nothing smaller than a cell is capable of growth and reproduction Bounded by a plasma membrane Contains a nucleus and cytoplasm Cell Membrane allows nutrients to enter the cell Cytoplasm gel like substance between nucleus and membrane contain organelles Organelles produce modify and secrete proteins enzymes that speed up the chemical reaction allowing the cell to grow and reproduce Nucleus centrally located command center Chromatin long stringy material that condenses and coils just before cell division to become chromosomes Youtube video Fertilization Conception https www youtube com watch v BFrVmDgh4v4 SEXUAL DIFFERENTIATION Chromosomes PSY 388 03 Normally 23 pairs 22 autosomes 1 pair sex chromosomes Generally o Males XY o Females XX o Chromosomes carry the genes Test Question THE HUMAN LIFE CYCLE Involves growth and sexual reproduction via processes below Mitosis growth repair Meiosis sexual reproduction CELL CYCLE MITOSIS WALTHER FLEMMING Mitosis Mitotic stage Mitosis Cytokinesis occurs o Mitosis asexual division of the nucleus o Number of division 1 o Number of cells 2 daughter cells genetically identical contain equal number of chromosomes o Function general growth and repair of the body Cytokinesis division of the cytoplasm organelles CELL CYCLE MITOSIS Steps 1 Cell divides 2 Enters in interphase interval of time between cell divisions a G1 organelles duplicate b G2 protein synthesis production occurs 3 Interphase 18 24 hours 4 Mitosis cytokinesis 1 2 hours Apoptosis programmed cell death Check point 1 is cell good If not stops cell cycle and allows time to repair damages so it s not passed on PSY 388 03 PSY 388 03 MITOSIS PSY 388 03 Youtube Video MITOSIS https www youtube com watch v cvlpmmvB m4 CELL CYCLE MITOSIS OSCAR HERTWIG Meiosis Occurs in the sex cells gametes in the sex organs gonads Number of division 2 Number of cells 4 daughter cells genetically different number of chromosomes reduced by half Function sexual reproduction creates female egg cells male sperm cells PSY 388 03 MEIOSIS PSY 388 03 Cross over genetic information is exchanged Youtube video Meiosis https www youtube com watch v D1 mQS FZ0 Page 14 on Reader Spermatogenesis production of sperm in testes Oogenesis production of eggs in ovaries Primary oocyte becomes large completes Meiosis I Forms secondary oocyte polar body product with chromosomes and little cytoplasm No further development beyond Meiosis I until Released one ovum at a time once a month during sexually mature menstrual cycle zygote Meiosis II completed only if fertilized by a sperm o When fertilized egg reaches maturity and it becomes zygote Occurs prior to birth unlike in males By week 20 fetus possesses all oocytes 4 million Before birth 1 million oocytes remain PSY 388 03 DEVELOPMENT OF MALE AND FEMALE PHYSIOLOGY Within the first 6 weeks of development no difference exists between male and female embryos Same internal reproductive system o Thus the capability of developing according to either the male or female pattern regardless of chromosomal pattern Initially male and female external genitalia are identical DEVELOPMENT OF MALE FEMALE SEX ORGANS Change in gonads depends on presence of a Y chromosome Y chromosome present Testosterone appears stimulates gonads to become testes Y chromosome NOT present Ovaries appear IMPORTANT Male or female depends on the SRY gene on the Y chromosome SRY gene must be present for fetus to develop male organs Wolffian System The capacity to develop according to the male pattern M llerian System The capacity to develop according to the female pattern DEVELOPMENT OF INTERNAL REPRODUCTIVE Testes ovaries are located inside the pelvic cavity Testes descend into the scrotal Ovaries remain in the abdominal sac cavity Wolffian System M llerian System for Male Female PSY 388 03 DEVELOPMENT OF MALE FEMALE EXTERNAL GENITALIA PSY 388 03 Week 6 a small bud appears between the legs can develop into a penis or clitoris depending chromosome Y Week 9 a urogenital groove bordered by 2 swellings appear Week 14 the groove disappears in males and the scrotum ahs formed and the grooves in females remains and becomes the vaginal opening MALE GENITALIA Testes produce testosterone sperm Penis external organ secretes fluids and substances o Erectile tissues contain distensible blood spaces o Rush of blood to the erectile tissues causes the penis to become erect Urethra in males is part of the urinary system and the reproductive system o A splinter closes off the bladder so no urine enters the urethra FEMALE GENITALIA Labia lips majora outer two folds of skin and fatty tissue on each side of the opening to the vagina o Covered with pubic hair vary in size Labia minora inner skin of the labia majora be smooth or wrinkled o Labia majora minora Vulva Clitoris anterior o Hairless vary in color pink to brown can change color after puberty can o Head or glands vary in size smaller than a pear or bigger than a child s finger homolog of penis sensitive erectile tissue sensory receptors o When stimulated clitoris becomes erect In females urinary and genital systems are separate CHROMOSMAL INHERITANCE Humans have 46 chromosomes 23 pairs 22 pairs autosomes non sex chromosomes 1 pair sex chromosomes Abnormal chromosomes number and structure disorders syndrome group of symptoms that always occur together Down Syndrome a total of 47 chromosomes gene at the bottom third of AUTOSOMAL SYNDROMES chromosome 21 Some Characteristics o Short stature PSY 388 03 o An eyelid fold o Stubby fingers o A wide gap between the 1st 2nd toes o Intellectual disability to varying degrees Chances are increased in women over 40 yrs o Age 40 or under 1 in 800 births for mothers o Age over 40 1 in 80 Cri du Chat missing portion of one chromosome 5 Some Characteristics o Small head o An eyelid fold o A cry sound like a cat s cry o Severe intellectual disability is evident as a child o 1 in 50 000 live births VARIATIONS IN SEXUAL DEVELOPMENT Errors in meiosis can ALTER THE SEX CHROMOSOMES o Abnormal sex chromosome number too many or too few X or Y chromosomes SEX CHROMOSOMAL SYNDROMES FEMALES Turner Syndromes a female XO at birth O signifies an absence of a second sex chromosomes Some Characteristics o Short stature o Small and underdeveloped breasts uterine tubs and o No functioning ovaries o Do not undergo puberty or menstruate o