1. Type A: magiging stem cells 2. Type B: become primary Spermatocyte

Cytogenetics Meiosis, Development, and Aging Flashcards by Gio Ebarola

Two divisions of the genetic material

Reduction Division (Meiosis 1)
Equational Division (Meiosis 2)

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Reduces the no. of replicated chromosomes from 46 to 23

Reduction Division (Meiosis I)

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Produces 4 cells from the 2 cells formed in the 1st division by splitting the replicated chromosomes

Equational Division (Meiosis II)

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Gametes are formed from special cells

Germline Cells

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Halved the chromosomes no during meiosis

Contribute 23 diff chromosomes, constituting 1 copy of the genome

Chromosomes pairs are Homologous pair: same genes in the same order but carries diff alleles

Haploid Cells

Gametes

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W/o meiosis, sperm and oocyte would each contain 46 chromosomes and the fertilized ovum have twice the normal no of chromosomes

Polyploid

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Occurs after an interphase period where DNA is being replicated

Reduction Meiosis (Meiosis I)

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The homologs exvhange parts or cross over

All 4 chromatids that comprise each homologous chromosome pairs aligh as exhage occur

After crossing over, each homolog bears some genes from each parent

New gene combinations arise from corssing over when the parents carry different alleles

Toward the end of prophase I, the synapsed chromosomes separate but remain attached at a few points along their lengths

Synapsis and Cross Over

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Different Phases of Reduction Meiosis (Meiosis I)

Prophase I
Metaphase I
Anaphase I
Telophase I

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Homologs align down the center of the cell

Each member of homologous pair attaches to a spindle fiber at an opposite pole

generates genetic diversity

Metaphase I

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Caused by random alignment of chromosomes

Means that the fate of a gene on 1 chromosome is not influenced by a gene on a different chromosome.

Accounts for the basic law of inheritance

Independent Assortement of Genes

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Homologs separte and move to opposite poles

Anaphase I

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Nuclear envelope partially assemble around chromosomes

Telophase I

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Divides cell into 2 haploid cells

Cytokinesis

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___ 4 Haploid Cell (each carrying a new assortment of genes and chromosomes that hold a single copy of the genome

Net Result

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The centromeres of each replicated chromosome in meiosis I remain together and unfold during

The single DNA replication, followed by the double division of meiosis, halves the chromosomes number: Haploid Cell

Equational Meiosis (Meiosis II)

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Where DNA replication happens

S-Phase

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Chromosomes become condensed and visibe again

Prophase II

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Align down the center of the cell

Metaphase II

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Centromeres part

Newly chromosomes formed (each has unreplicated form)

Anaphase II

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Nuclear enveloped form around the four nuclei, which then separate into individual cells

Telophase II

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Formation of sperm cells

Spermatogenesis

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Diploid stem cell of sperm

Divides mitotically to form 2 daughter cells

Spermatogonium

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2 Daughter cells

Type A: magiging stem cells
Type B: become primary Spermatocyte

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Forms 2 haploid cells called secondary Spermatocytes

Primary Spermatocytes

Primary to Secondary Spermatocyte

Meiosis I

Spermatid to Sperm

Meiosis II

Divides to yield 2 equal-sized spermatids in the replicated form

Secondary Spermatocyte

Spermatid elongates and sheds its excess cytoplasm Spermatids develop sperm flagellum

Spermiogenesis (Maturation)

Produces Sperm/Spermatozoa

Spermiogenesis (Maturation)

Anatomy of Sperm

Head Midpiece Tail

Contains Genetic Material (DNA)

Head

Mitochondria of the sperm

Midpiece

Locomotor of the sperm

Tail

Begins when a oogonium that self renews and also yields a lineage whose cells differentiate

Oogenesis

Stem cells of ooctyes

Oogonium/Oogonia

As it grows: Cytoplasm accumulates DNA replicates Becomes Primary Oocytes

Oogonium/Oogonia

Primary-Secondary Oocyte

Meiosis I

Production only occurs in fetus Divides into 2 cells called First Polar Body Each cell is haploid w/ 1 chromosome set and in replicated form Meiosis is arrested in late PROPHASE I and resumes during puberty

Primary Oocyte

Secondary Oocyte-Ovum

Meiosis II

Divides unequally in meiosis II to produce another small polar body w/ unreplicated chromosomes If it's NOT fertilized by a sperm: It will yield an ovum and tiny second polar body Meiosis is arrested during METAPHSE II and resumes only after fertilzation

Secondary Oocyte

For the first 8 weeks Rudiments of all body parts form Begin when the fertilized ovum divides by mitosis

Prenatal Human: Embryo

9th week until birth Structure grow and specialize

Prenatal Development After 8th week fetus

Sperm's chromosomes combine with an egg cell to form a fertilized egg

Zygote

Within 12 hours of the sperm's penetration, the ovum's nuclear membrane disassembles, and the two sets of chromosones, called Pronuclei

Fertilization

A biochemical process in which sperms can penetrate the ovum

Capacitation

Release of acrosomal enzymes so the sperm can bind to the egg's zona pellucida

Acrosomal Reaction

Protective layer of egg cell

Zona Pellucida

Frequent cell division of zygote

Cleavage

A day after fertilization, zygote divides by mitosis

Embryo Cleaves and Implants

Product of cleavage 2 Identical cells Formed after 36 hours of fertilization

Blastomeres

Formed when blastomeres form a solid ball of 16/ more cells Formed after 72 hours of fertilization

Morula

The ball of cells hollow out, and its center fills with fluid, creating a blastocyst

Blastocyst

Continues developing, forming the embryo

Inner Cell Mass

When blastocytes nestles into the uterine lining

Implantation

Occurs after a week of fertilization

Implantation

HCG that prevents means and sign of pregnancy

Trophoblast

What is HCG

Secrete Human Chorionic Gonadotropin Hormone

Forms between the inner cell mass and outer cells anchored to the uterine lining

Amniotic Cavity

Cells that forms the primordial Embryo Progressive switches off the expression of genes

Primary Germ Layers

Layer nearest to amniotic cavity

Ectoderm

Primary Germ Layers

Ectoderm Mesoderm Endoderm

Middle layer of primary germ

Mesoderm

Inner layer Closer to the blastocyst activity

Endoderm

Chorionic Villi forms Mother's and embryo's blood system separate but nutrients and oxygen diffuse across the chorionic villi

3rd Week

Placenta is fully formed Umbilical cord forms

10th Week

The yolk sac shrinks Amniotic sac swells with fluid that cushions the embryo and maintains constand temp and pressure Amniotic Fluid contains Fetal Urine and Few Fetal Cells

By the End of embryonic Period,

Anatomical Seces appear after SRY gene is expressed in males

6th Week

Ferus sucks its thumb, kicks, make fists, and faces Has beginnings of teeth Breathes amniotic fluid in and out Urinates and defecates First Trimester ENDS

12th Week

Fetus has hair, eyebrows, lashes, nipples, and nails

17th Week (4th month)

Vocal cords formed but makes no sound

18th week (5th month)

Fetus curls into a head-to-knees positions Weighs about 454 g (1 pound)

By the end of 5th month

Skin appears wrinkled because there isn't much fat beneath it

6th Month

The fetus kicks, jabs, and even hiccups 23 cm (9 inches) long

By the end of 2nd Trimester

Fetal brain cells rapidly link into networks as organs elaborate and grow Digestive and Respiratory System matures last

Final Trimester

Results when 2 sperm fertilize 2 oocytes Can happen if ovulation occurs in 2 ovaries in the same mothn/ if 2 oocytes leave the same ovary and are both fertilized

Fraternal / Dizygotic Twins

Descend from a single fertilized ovum and therefore genetically identical Natural clones

Identical / Monozygotic Twins

Time when genetic abnormalities, toxic subtstances, or viruses can alter a specific embryonic structure

Critical Period

Extermely rare, progressive genetic disorder Children age rapidly (starts from the 1st 2 yrs of their life)

Progeria

Anything a person is exposed to during pregnancy that causes abnormalities Cause congenital disorders

Teratogens

Causes birth defects Used to prevent seizures and symptoms of bipolar disorder Rarely, it can cause NTDs, heart defects, hernias, and clubfoot Woman ho have a gene variant (MTHFR C677T) can use other alternative drugs to treat seizures and bipolar

Valproic Acid

Can cause intellectual impairment and poor social skills from prenatal exposure to the drug Can cause poor self-control, difficulty processing info, and attention deficit in childhood

Cocaine

Higher risk of language and memory problems and anxiety in adolescence

Cocaine

CO prevents the fetus' oxyhemoglobin binding

Cigarettes

___ can be dangerous as well

Vaping

Nicotine can cause:

Sudden infant death syndrome Low birth weight Hearing problems in childhood

Has tetragenic effects Used to treat Leprosy, AIDS and certain blood and bone marrow cancers

Thalidomide

A rare congenital anomaly where the proximal aspect of an extremity is absent with the hand or foot attached directly to the trunk

Phocomelia

Can cause behaviour poblems, communication challenges, abnormal cognition, hyperactivity, and short attention span

Alcohol

More likely to have hearing and visual loss

Alcohol

Caused by alcohol consumption during pregnancy

Fetal alcohol spectrum disorders

Most severe manifestation of alcohol exposure Children have small heads and flat faces Growth is slow before and after birth Teens are short and have small heads Many adults with FAS function at early grade-school level. They never develop social and communication skills and cannot undeaths the consequences of actions.

Fetal Alcohol Syndrome

Ingestion of large amounts of vitamins, drugs, etc

Nutrients

Vitamin A Causes spontaneous abortion and defdects of heart, NS, and face in expose embryo

Isotretinoin

After birth, when the vitamin supply suddenly plummets, the baby may develop symptoms of vitamin C deficiency, such as bruising and becoming infected easily.

Excess Vitamin C

Poor nutrition later in pregnancy affects the development of the placenta and can cause low birth weight, short stature, tooth decay, delayed secual development, and learning disabilities.

Malnutrition is

Can cause microcephaly have a spectrum of neurological problems, including difficulty with mobility, seizeuers, sleep problems, and poor hearing and vision

Zika Virus

What is microcephaly

Small brain

Higher risk for low birth weight, prematurity, and stillbirth if the woman's health is failing

HIV

Exposure during the first trimester of pregnancy caused cataracts, deafness, and heart defects

German Measles (Rubella)

Means moving through the life cycle despite advertisements for products that promise to reverse the process

Aging

Most dominantly inherited conditions start to affect health in early to middle adulthood

Adult-Onset Inherited Disease

Syndromes that Resemles Accelerated Aging

Ataxia Telangiaectasia Cockayne syndrome Hutchinson Gillford progesria syndrome

Most severe rapid again condition Normal cells growing in culture divide about 50 times before dying.

Hutchison = Gillford Progeria

Aging reflects gene activity plus a lifetime of environmental influences

Genes and Longetivity

Families and genetically isolated populations with many aged members have a lucky collection of gene variants plus shred environmetal influences such as good nutrition, excellent health are, and devoted relatives

Genes and Longetivity

Cytogenetics Meiosis, Development, and Aging Flashcards

(106 cards)