IntroductionIntroduction

• Need to start small Need to start small end big end big• Cells, molecules Cells, molecules populations, populations,

ecosystemsecosystems• To understand role of sex in humans, To understand role of sex in humans,

need to understand human role in need to understand human role in environment (natural world)environment (natural world)

• Will learn one step at a time Will learn one step at a time class class builds on earlier parts so make sure builds on earlier parts so make sure you are here for all partsyou are here for all parts

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Chapter 1

Chromosomes and

Chromosomal Inheritance

Review of The Human CellReview of The Human Cell

• Smallest unit of lifeSmallest unit of life• All bounded by plasma membrane and All bounded by plasma membrane and

have nucleus and cytoplasmhave nucleus and cytoplasm– Nucleus Nucleus contains contains chromatinchromatin condense condense

at cell division (cell reproduction) to form at cell division (cell reproduction) to form chromosomeschromosomes

– All human body cells (called All human body cells (called somatic cellssomatic cells) ) have 46 chromosomes arranged as 23 have 46 chromosomes arranged as 23 matched pairsmatched pairs

– 1/2 of pair from Mom, ½ of pair from Dad1/2 of pair from Mom, ½ of pair from Dad– Chromosomes carry Chromosomes carry genes genes determine determine

structure and function of cellstructure and function of cell

Other cell partsOther cell parts• Cytoplasm (consistency of olive oil) Cytoplasm (consistency of olive oil)

contains cell organellescontains cell organelles– Endoplasmic reticulum (ER)Endoplasmic reticulum (ER)

• Rough ERRough ER contains ribosomes that are used for contains ribosomes that are used for protein synthesisprotein synthesis

• Smooth ERSmooth ER detoxification (pepper juice, alcohol, detoxification (pepper juice, alcohol, aspirin, etc)aspirin, etc)

– VesiclesVesicles – storage sacks – storage sacks– Golgi apparatusGolgi apparatus – modify proteins – modify proteins– LysosomesLysosomes – contain digestive enzymes – contain digestive enzymes– MitochondriaMitochondria – produce energy in cell using – produce energy in cell using

oxygen, produce COoxygen, produce CO22 as waste product (both as waste product (both carried in blood by __________ cells )carried in blood by __________ cells )

Fig. 01-01 Cell StructureFig. 01-01 Cell Structure

Human Life CycleHuman Life Cycle• Consists of growth and sexual reproductionConsists of growth and sexual reproduction• During growth, process of During growth, process of mitosismitosis produces produces

new chromosomes for new body cells (number new chromosomes for new body cells (number = 2n)= 2n)

• Some new cells are sex cells (called Some new cells are sex cells (called gametesgametes = = sperm, eggs) sperm, eggs) need to have ½ normal number need to have ½ normal number (called n) of chromosomes (why?) (called n) of chromosomes (why?)

• For sex cell ½ number of chromosomes For sex cell ½ number of chromosomes produced by process called produced by process called meiosismeiosis happens happens in in gonadsgonads (testes, ovary) (testes, ovary)

• Union of sex cells called fertilization Union of sex cells called fertilization producing a __________ (fertilized egg)producing a __________ (fertilized egg)

• Zygote grows up to adult, takes Biology of Sex Zygote grows up to adult, takes Biology of Sex class, eventually has baby class, eventually has baby completes human completes human life cyclelife cycle

Fig. 01-03 Life cycle of humansFig. 01-03 Life cycle of humans

MitosisMitosis

• MitosisMitosis is the is the process of forming process of forming a new set of a new set of chromosomes prior chromosomes prior to cell divisionto cell division

• Chromosome Chromosome number starts at 2n number starts at 2n (46 in humans) in (46 in humans) in one cell and ends one cell and ends up with 2n in two up with 2n in two daughter cellsdaughter cells Fig. 01-05 Fig. 01-05

MitosisMitosis

MeiosisMeiosis• Meiosis is a two step Meiosis is a two step

processprocess• Meiosis I is similar to Meiosis I is similar to

mitosis (end up with 2n mitosis (end up with 2n chromosomes) but then the chromosomes) but then the two daughter cells split two daughter cells split again without forming new again without forming new chromosomes (called chromosomes (called Meiosis II) Meiosis II)

• This results in four This results in four daughter cells, each with n daughter cells, each with n number of chromosomes number of chromosomes (23 in humans). (23 in humans).

• This is how both sperm and This is how both sperm and egg cells are formed.egg cells are formed.

Fig. 01-09 Fig. 01-09 MeiosisMeiosis

Fig. 01-12 Spermatogenesis and Fig. 01-12 Spermatogenesis and OogenesisOogenesis

Reproductive Reproductive CloningCloning

• Asexual reproduction – only need Asexual reproduction – only need one parentone parent

• Off-spring are genetically Off-spring are genetically identical to parentidentical to parent

• 11stst mammal ever cloned = a mammal ever cloned = a sheep! sheep! – egg taken from a sheep egg taken from a sheep – nucleus (with genetic material) nucleus (with genetic material)

removed, then fused with normal removed, then fused with normal body cell of a different sheep body cell of a different sheep

– egg started to grow and divide egg started to grow and divide – grew to become a whole sheep --> grew to become a whole sheep -->

Dolly! Dolly!

• Research on human cloning Research on human cloning banned by _______________ .banned by _______________ .

Fig. 1AFig. 1AProposed Proposed

human clonehuman clone

Chromosomal Chromosomal InheritanceInheritance

• In humans In humans 22 prs of chromosomes 22 prs of chromosomes are are autosomesautosomes (nonsex chromosomes) (nonsex chromosomes) and one pair is the and one pair is the sexsex chromosomes chromosomes (differ between sexes)(differ between sexes)

• Can have problems when have Can have problems when have abnormal chromosome number and abnormal chromosome number and structurestructure

• Problems called Problems called syndromessyndromes – group of – group of symptoms that always occur togethersymptoms that always occur together

Autosomal SyndromesAutosomal Syndromes

A.A. Down SyndromeDown Syndrome – – fertilization results fertilization results in extra in extra chromosome #23 chromosome #23 (could be from (could be from mother mother or or father)father)

- - results in shortness, results in shortness, eyelid fold, stubby eyelid fold, stubby fingers, a large fingers, a large fissured tongue, fissured tongue, round head, palm-round head, palm-crease and moderate crease and moderate to severe mental to severe mental retardationretardation

Autosomal Syndromes Autosomal Syndromes (con’t)(con’t)

B.B. Cri du Chat Cri du Chat SyndromeSyndrome – caused by – caused by chromosomal deletionchromosomal deletion (loss of part of (loss of part of chromosome) of chromosome) of chromosome #5.chromosome #5.

1.1. Infants – moon-shaped Infants – moon-shaped face, small head, cry that face, small head, cry that sounds like a cat’s cry sounds like a cat’s cry due to mal-formed due to mal-formed larynx.larynx.

2.2. Older child – eye-lid fold, Older child – eye-lid fold, misshapen ears placed misshapen ears placed low on head, severe low on head, severe mental retardationmental retardation

Fig. 01-15 Cri du Chat Fig. 01-15 Cri du Chat syndromesyndrome

Sex Chromosome Sex Chromosome SyndromesSyndromes

The gender of a child The gender of a child is determined by is determined by the father’s the father’s sperm at sperm at conceptionconception

TA 01-01TA 01-01

• Males have “Y” Males have “Y” sex chromosome sex chromosome paired with an “X” paired with an “X” sex chromosomesex chromosome• Females have two Females have two X chromosomesX chromosomes

Sex Chromosome Sex Chromosome SyndromesSyndromes

(Abnormal Sex Chromosome Number)(Abnormal Sex Chromosome Number)A.A. Turner SyndromeTurner Syndrome – individual with only one X – individual with only one X

chromosome so have XO (O = absence of second chromosome so have XO (O = absence of second sex chromosome). Always female because sex chromosome). Always female because no Y no Y chromosomechromosome..

1.1. Short, with a broad chest and folds of skin on back of Short, with a broad chest and folds of skin on back of neckneck

2.2. Ovaries, oviducts, and uterus are small and Ovaries, oviducts, and uterus are small and underdevelopedunderdeveloped

3.3. Do not undergo puberty or menstruate (have period)Do not undergo puberty or menstruate (have period)4.4. Breasts do not develop.Breasts do not develop.

B.B. Klinefelter SyndromeKlinefelter Syndrome – a male with two or more X – a male with two or more X chromosomes in addition to Y chromosomechromosomes in addition to Y chromosome

1.1. Testes and prostate gland are underdeveloped (usually Testes and prostate gland are underdeveloped (usually sterile)sterile)

2.2. No facial hairNo facial hair3.3. May have some breast developmentMay have some breast development4.4. Very long arms and legs, and large hands and feetVery long arms and legs, and large hands and feet

Fig. 01-16Fig. 01-16

Female with Turner (XO) Syndrome Male with Klinefelter’s Syndrome