Bio Cell Cycle And Reproduction Flashcards
The mechanism by which cells Dunlop ate their content and divide is controlled by?
Checkpoints or restriction enzymes within the cell cycle
In what stage of cell cycle most human cells are arrested?
G0
Cell cycle stages
G0 = cell cycle arrest, resting phase.
G1 (following with G1/S checkpoint) = presynthetic growth, organelle duplication, preparation a cell for division.
S phase = DNA synthesis and replication.
G2 ( following with G2/M checkpoint) = premitotic growth, dna damage repair, DNA is checked for errors.
M phase = cell division via mitosis and cytokinesis
Interphase consists of G1 and G2 separated by S phase
In order to compete one cycle, a cell starting at any phase must pass through all phases and return to the phase in which it begin
Checkpoints control the process by which cells replicate their content and divide, they ensure all steps of the cycle have been executed in the correct manner. They are regulated by cyclines and cyclin dependent kinases. If cell has abnormalities that cannot be repaired, these cells undergo apoptosis.
What is gonads?
Males testes and female ovaries
Reproductive glands that produce gametes
Male reproductive system; organs and its functions?
Prostate- prostatic fluid production containing enzymes necessary to prevent the coagulation of sperm in the vagina
Urethra - sperm transport
Penis- sexual intercourse
Testis - sperm production
Epididymis - sperm maturation and storage until release
Ductus ( vas) deferens (семявыносящий проток) - sperm transport to the urethra
Bulbourethral (cowpers) gland - thick, alkaline mucus secretion
Seminal gland - seminal fluid production
Female reproductive anatomy
Spermatogenesis steps
The testes contain specialized structures called seminiferous tubules (канальцы)- location to sperm production
1) spermatogonia undergoes mitosis forming two identical daughter cells
2) one of the daughter cells remains a spermatogonium while the other becomes a primary spermatocyte and begins meiosis 1 resulting in two secondary spermatocytes.
3) four spermatids are produce by the end of Meiosis 2.
4) then they become spermatozoa which migrated to the epididymis for maturation and acquire motility
The seminiferous tubules also contain:
Sertoli cells- supplies nutrients to developing sperm
Leydig cell - secretes testosterone
Spermatozoa structure
Head, mid piece, tail
Steroid hormones
Meiosis
Prophase, metaphase, anaphase, telophase
Meiosis 1 for homologous chromosomes
Meiosis 2 for sister chromatids
Mitosis
Two identical daughter
1) prophase. DNA coil to make condensed sister chromatids. Each pair of sister chromatids are joined with kinetochore in the middle. Due to the end, nuclear envelope breaks down. Centrosomes migrate to the opposite poles within the cell, the mitotic spindle is formed.
2) metaphase. Spindle fibers are attached to kinetochore of chromosomes and they are lined on the metaphase plate in the middle of the cell
3) anaphase - sister chromatids are pulled apart by spindle fibers and moved on the opposite poles of the cell forming two sets of chromosomes within the cell
4) telophase - chromosomes decondensed and nuclear envelope is formed around each chromosome. And the parental cell undergoes cytokinesis ( cytoplasmic division)
Cytokinesis - division of cell membrane forms two identical daughter cells
What is gastrulation?
Process by which the gem layers ( endoderm, mesoderm, ectoderm) form in the developing embryo.
Following fertilization, zygote undergoes cleavage and forms the blastula then into the blastocyst which is divided into to layers, then it transforms into three layer structure- glastula.
Layers:
endoderm ( inner layer) - digestive organs like liver, pancreas and the epithelium of the digestive and respiratory tracts like islet beta cells, alveolar cells, mucous cells.
Mesoderm ( middle layer)- myocytes, osteocytes, erythrocytes, muscles, bones, circulatory system, parts of the urinary and reproductive systems.
Ectoderm ( outermost layer)- nervous system, hairc skin, nails, anus, nostrils, lining of the mouth, epidermis, neurons, melanocytes, astrocytes, retinal neurons
Haploid means .. while diploid
23 chromosomes
46 chromosomes
How zygote becomes an embryo?
Zygote undergoes first round of mitosis and other rounds and cell differentiation forming an embryo
Types of stem cells during potency?
Totipotent : able to differentiate into both placental and fetal structures, have the greatest potency.
Pluripotent: give rise to only fetal cells but not placental, to any of the three primary germ layers footing in the embryo.
Multipotent: able to differentiate into specialized cell types of a particular tissue, also found in adults.
Difference between cell determination and differentiation?
Determination= specification of cell fate
Differentiation- acquisition of unique specialized biochemical and structural cellular characteristics in the embryo result from asymmetric segregation and inductive signaling, different gene expression patterns result in the specific features.
What is inductive signaling?
An inducer ( signaling cell) releases chemical signals that act on competent neighboring cells by regulation the expression of specific genes. This signaling provides the competent cells with position and fate for proper development.
Morphogen characteristics
It is a signaling molecule in a induction signaling whose concentration patterns influence cell differentiation. They are released by signaling molecules and diffuse outward to alter gene expression in competent cell in a concentration dependent manner making a concentration gradient.
A type of paraffins factor that helps control organ development and body formation.
Fertilization and implantation picture
When abnormal activated apoptosis occur?
During oxidative stress = when ROS such as peroxides and superoxide are excessive and damaging the cells and higher cellular concentration of free radicals.
DNA replication graph
What is standard error of the mean? (SEM)
Provides information in the precision of a measurement, how close the calculated mean value for an experimental group is true mean for the population.
Smaller SEM= mean is closer to the population.
SEM directly depends on SD and inversely in the sample size
Mean median mode
Transcription by RNA polymerase
Neurulation process
Formation of the nervous system.
After gastrulation, the notochord forms the neural plate that creates the neural tube which is precursor of the CNS.
Neural crest cells migrate away from the tube to five rise to periphery nervous system.
CNS glial cells ( support neural function?
Oligodendrodytes: myelinate multiple axons.
Astrocytes: help form blood brain barrier
Microglia: phagocytose waste
Ependymal cell: create barriers
Glial cells of peripheral nervous system
Satellite cells: support cell bodies
Schwann cell: myelinate single axons
Structure of neuron
Nervous system cells consists of neurons (conduct electrical signals) and glial cells ( support neural function)
Axon, synapse, soma
Oogenesis steps
Process by which females produce sex cell called eggs ( oocytes)
At birth, their maturation is arrested in prophase 1 known as primary oocytes. At puberty, when the menstrual cycle begins, each month a single primary oocytes develops into a secondary oocytes by continuing meiosis up to metaphase 2.
Maturation and growth of the follicle is driven by the release of FSH from the anterior pituitary. The release of LH stimulate follicle rupture and the release of the secondary oocyte Bragg the opening fallopian tube (ovulation) to form ovum.
Fallopian cilia help propel the fertilized oocyte toward the uterus for implantation.
Menstrual period hormones
Pituitary gland hormones
Prolactin, ACTH, FSH, TSH, LH, GH
Oxytocin, vasopressin
Steps of fertilization when the sperm reaches the oocyte
1) sperm reaches oocyte
2) sperm contact- sperm binds receptors in the zona pellucida
3) acrosome reaction - hydrolytic enzymes degrade the zona pellucida enabling the sperm to reach the oocytes plasma membrane
4) fusion - plasma membrane of the oocyte and sperm are fused
5) sperm contents enter oocyte
6) cortical reaction - hardens zona pellucida blocking additional sperm from entering
What is chromosomal nondisjjnction?
When homologous chromosomes during meiosis 1 or sister chromatids during meiosis 2 fail to separate to opposite poles of the cell during anaphase. This lead to extra chromosome in some daughter cells and missing chromosomes in others
Embryogenesis stages
1) fertilization- fusion of sperm and oocyte results in a single called zygote
2) morula formation - zygote undergoes mitotic divisions to form a ball of cells as morula
3) blastulation - formation of blastocyst ( two layers: throphoblast and the inner cell mass inside the throphoblast)
4) gastrulation - germ layers and glastula
5) neurulation - nervous system formation form notochorm
Spermatogenesis and oogenesis characteristics
Cellular communication occurs
Through direct contact between adjacent cells and secretion of short and longer range signaling molecules trigger signaling cascades that results in different expression or repression of genes
Types of microtubules
Intercellular transport of cargo ( organelles, vesicles)
Kinesin ( anterograde transport- away from the nucleus toward distal sites, away from cell body)
Dynein ( retrograde- from distal sites to the nucleus toward cell body)
Transcription activator and repressors
What is fitness?
Reproductive success
Genetic diversity and reproduction relation
Low genetic diversity via mitosis asexually
High genetic diversity via meiosis sexually
What is regeneration?
Regrowth of the same functional organs or tissues present in an organism after loss due to injury
Role in producing new cartilage cells
Female reproductive system
Fallopian tube - location of fertilization
Ovary - produces oocytes and secretes hormones
Uterus - protects and nourishes developing embryo and fetus
Endometrium - inner lining of the uterus
Myometrium - layer of smooth muscle
Cervix - inferior portion of uterus, connect to vagina
Vagina - birth canal, receives penis, passageway for menstrual fluids
Function of tumor suppressor genes?
Regulate DNA repair by pausing or repressing the cell cycle. Programmed cell death is induced in cells that cannot be repaired. In cancer cell, these genes are inhibited.
Effects of estrogen and progesterone
Synthesized and secretes by ovaries
Normal: breast development, fertility, bone mass
Withdrawal: inrritability, fatigue, anxiety, breast atrophy, infertility, decreased bone density
Blood vessels types
Vasoconstriction: decrease of blood vessel diameter, decrease of blood flow, high blood pressure
Vasodilation: Hugh vessel diameter, high blood flow, low blood pressure
Transport blood throughout the body. Consists of endothelium unaided then smooth muscle and then connective issue
Structure of mature sperm
Head with acrosome containing enzymes to aid fertilization and nucleus
Centrioles
Midpiece with mitochondrial spiral that generates ATP required for flagellum sperm motility
Microtubules and tail (flagellum) for motility
