2C: Processes of cell division, differentiation and specialization Flashcards
Autosomal Cells
Diploid (2n) = 46
Haploid Cells
Haploid (n) = 23
Interphase
Consists of G1, S, G2; actively dividing cells spend most of their time in this phase
Interphase
Consists of G1, S, G2; actively dividing cells spend most of their time in this phase
G0
The cell is simply living and serving its function without any preparation for division
Interphase
Consists of G1, S, G2; actively dividing cells spend most of their time in this phase;
Chromosomes are in less condensed form known as chromatin (so that DNA is available for RNA Pol to transcribe)
G0
The cell is simply living and serving its function without any preparation for division
G1 Stage [Presynthetic Gap]
Cell creates organelles for energy and produces proteins while increases their size; contains a restriction point
G1 Stage [Presynthetic Gap]
Cell creates organelles for energy and produces proteins while increases their size; contains a restriction point
S Stage [Synthesis]
Genetic material is replicated so that each daughter cell will have an identical copy; each chromosome consists of two identical chromatids after replication
G2 Stage [Postsynthetic Gap]
Cell passes through another quality control checkpoint - makes sure that there are enough organelles and cytoplasm for both daughter cells
M Stage [Mitosis]
Consists of Prophase, Metaphase, Anaphase, Telophase and Cytokinesis
M Stage [Mitosis]
Consists of Prophase, Metaphase, Anaphase, Telophase and Cytokinesis
Prophase
Nucleus disappears, spindle forms, DNA condenses into chromosomes
Metaphase
Sister chromatids align along the equator of the cell by attaching their centromeres to the spindle fibers
Anaphase
Sister chromatids separate at the centromere and are pulled toward opposite poles of the cell by the mitotic spindle
Prophase
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate and spindle apparatus forms
Metaphase
Chromosomes align along the equator of the cell by attaching their centromeres to the spindle fibers
Anaphase
Sister chromatids separate at the centromere and are pulled toward opposite poles of the cell by the mitotic spindle
Telophase
Nuclear membrane reforms and spindle apparatus disappears
Cyclins & Cyclin-Dependent Kinases
Rise and fall during the cell cycle controlling the activity of the cell cycle
Cancer
Occurs when cell cycle control becomes deranged, allowing damaged cells to undergo mitosis without regard for quality or quantity of the new cells produced
Metastasize
When cancerous cells produce factors that allow them to escape their site and invade elsewhere
Cyokinesis
Cytosol and organelles are split between the two daughter cells
Centriole Function
Organize the centrosome
Aster Function
Formed around each centrosome
Kinetochore
Protein structure on chromatids where spindle fibers attach during cell division
Kinetochore
Protein structure on chromatids where spindle fibers attach during cell division
Nuclear Membrane Breakdown
During Prophase and allows microtubules to attach at kinetochore
Nuclear Membrane Reorganization
During Telophase
How do chromosomes move?
By use of the spindle fibers during metaphase
Reasons for Growth Arrest
Genomic mutation/damage
Lack of nutrients
Contact Inhibition (once they get in contact with other cells they stop)
Reasons for Growth Arrest
Genomic mutation/damage
Lack of nutrients
Contact Inhibition (once they get in contact with other cells they stop)
Mechanisms that Control the Cell Cycle
Checkpoints within the cycle itself (G1 and G2), Spindle checkpoint; cyclins and CDK
Mechanisms that Control the Cell Cycle
Checkpoints within the cycle itself (G1 and G2), Spindle checkpoint; cyclins and CDK
Oncogenes
Genes that have the potential to cause cancer; can be due to mutations or excessive expression
Apoptosis
Programmed cell death; the cells contents are not released to the environment but rather digested intracellularly
Triggers of Apotosis
Cell Damage
Cell Mutations
Developmental Mechanisms
Immune Response
Prophase
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate and spindle apparatus forms
Cytokinesis
Cytosol and organelles are split between the two daughter cells
Triggers of Apotosis
Cell Damage
Cell Mutations
Developmental Mechanisms
Immune Response
Meiosis
Produces four non-identical haploid sex cells (gametes)
Rounds of Meiotic Division
- Reductional
2. Equational
Meiosis I
Homologous pairs of chromosomes are separated from each other
Homologues
Chromosomes that are given the same number but are of opposite parental origin
Prophase I
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate and spindle apparatus forms; additionally synapsis and crossing over occurs
Prophase I
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate and spindle apparatus forms; additionally synapsis and crossing over occurs
Metaphase I
Homologues line up on opposite sides of the metaphase plate
Anaphase I
Homologues segregate to opposite poles of the cell
-Accounts for segregation and independent assortment
Anaphase I
Homologues segregate to opposite poles of the cell
-Accounts for segregation and independent assortment
Telophase I
Chromosomes decondense and the cell may enter interkinesis
Telophase I
Chromosomes decondense and the cell may enter interkinesis
Meiosis II
Same process as Mitosis
Spermatogenesis Outline
Spermatogonium -> Primary Spermatocyte -> Secondary Spermatocyte -> Spermatid
Spermatogenesis Outline
Spermatogonium -> Primary Spermatocyte -> Secondary Spermatocyte -> Spermatid
Spermatogonium
[2n]
A diploid cell that undergoes mitosis and creates a primary spermatocyte
Primary Spermatocyte
[2n]
Undergoes Meiosis I and produces a secondary spermatocyte
Secondary Spermatocyte
[n]
Undergoes Meiosis II and produces a spermatid
Spermatid
[n]
Matures into sperm
Oogenesis Outline
Oogonium -> Primary Oocyte -> Secondary Oocyte -> Ovum
Oogonium
[2n]
A diploid cell that undergoes mitosis to produce a primary oocyte
Primary Oocyte
[2n]
A diploid cell that undergoes meiosis I to produce a secondary oocyte
Secondary Oocyte
[n]
A haploid cell that undergoes meiosis II to produce an ovum
Site of Sperm Development
Seminiferous Tubules of the Testes
Sertoli Cells
Nourish sperm
Interstitial Cells of Leydig
Secretes testosterone and other androgens
Scrotum
Site of the testes
Epididymis
Give sperm motility and store sperm until ejaculation
Epididymis
Give sperm motility and store sperm until ejaculation
Ejaculation Pathway
Vas Deferens -> Ejaculatory Duct -> Urethra -> Penis
Seminal Vesicles
Contribute fructose to nourish sperm and produce alkaline fluid
Prostate Gland
Also produces alkaline fluid
Bulbourethral Glands
Produce clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
Bulbourethral Glands
Produce clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
Semen
Composed of sperm and seminal fluid from the bulbourethral glands, seminal vesicles and prostate glands
Semen
Composed of sperm and seminal fluid from the bulbourethral glands, seminal vesicles and prostate glands
Sperm Structure
Head, Midpiece and Flagellum
Head of Sperm
Contains genetic material and covered in an acrosome that contains enzymes that help the sperm fuse and penetrate the ovum
Midpiece of Sperm
Generates ATP from fructose and contains many mitochondria
Flagellum of Sperm
Promotes motility
Flagellum of Sperm
Promotes motility
Ovum (Ova)
Produced in the follicles of the ovaries
Ovum (Ova)
Produced in the follicles of the ovaries
Polar Body
Uneven portion of the cytokinesis product in oogenesis
Polar Body
Uneven portion of the cytokinesis product in oogenesis
Zona Pellucida
Surrounds oocytes which is an acellular mixture of glycoproteins that protects the oocyte and contain the compounds necessary for sperm binding
Corona Radiata
A layer of cells that adhere to the oocyte during ovulation
Corona Radiata
A layer of cells that adhere to the oocyte during ovulation
Gonadotropin-releasing Hormone
Released from the hypothalamus and causes the release of FSH and LH
Function of FSH in Males
Stimulates sertoli cells and triggers spermatogenesis
Function of LH in Males
Stimulates interstitial cells to produce testosterone
Function of Testosterone
Responsible for maintenance and development of the male reproductive system and male secondary sex characteristics
Function of Testosterone
Responsible for maintenance and development of the male reproductive system and male secondary sex characteristics
Function of FSH in Females
Stimulates development of the ovarian follicles; produce estrogen and progesterone
Function of LH in Females
Stimulates ovulation; produce estrogen and progesterone
Primary Oocyte
[2n]
A diploid cell that undergoes meiosis I to produce a secondary oocyte
[Arrests in Prophase I]
Secondary Oocyte
[n]
A haploid cell that undergoes meiosis II to produce an ovum
[Arrests in Metaphase II]
Function of LH in Females
Stimulates ovulation; produce estrogen and progesterone
Reproductive Sequence
Fertilization -> Implantation -> Development -> Birth
Reproductive Sequence
Fertilization -> Implantation -> Development -> Birth
Menstrual Cycle Sequence
Follicular Phase -> Ovulation -> Luteal Phase -> Menstruation
Follicular Phase
GnRH stimulates FSH and LH which promotes follicle development; estrogen is released which stimulates vascularization and glandularization of the decidua (uterine lining)
Ovulation
Stimulated by a surge of LH; surge due to estrogens positive feedback effects
Luteal Phase
LH promotes the ruptured follicle to become the corpus luteum which secretes progesterone that maintains the uterine lining.
Negative Feedback of GnRH, LH and FSH
Caused by high levels of estrogen and progesterone
Menstruation
Occurs if there is no fertilization; endometrial lining is broken off and the block on GnRH production is removed
Fertilization Effects
Blastula produces hcG which maintains the corpus luteum
Menopause
Occurs when the ovaries stop producing estrogen and progesterone
Menopause
Occurs when the ovaries stop producing estrogen and progesterone
Implantation Sequence
Zygote -> Morula -> Blastocyst
Developmental Sequence
Blastocyst -> Gastrula -> Neurula
Developmental Sequence
Blastocyst -> Gastrula -> Neurula
Where does fertilization occur?
In the ampulla of the fallopian tube
What happens after the sperm penetrates the corona radiata and zona pellucida?
The sperm establishes the acrosomal apparatus and injects its nucleus; it also releases calcium ions that prevent additional sperm from fertilizing the ovum
What is a cortical reaction?
The reaction that prevents additional sperm from fertilizing the egg and increases the metabolic rate of the zygote
What is a cortical reaction?
The reaction that prevents additional sperm from fertilizing the egg and increases the metabolic rate of the zygote
How do dizygotic twins form?
Two eggs are fertilized by two different sperm
How do monozygotic twins form?
Splitting of a zygote into two
How do dizygotic (fraternal) twins form?
Two eggs are fertilized by two different sperm
How do monozygotic (identical) twins form?
Splitting of a zygote into two
How do monozygotic (identical) twins form?
Splitting of a zygote into two
Cleavage
Early divisions of cells in the embryo; resulting in a larger number of small cells but the volume remains the same
When is the zygote considered an embryo?
After the first cleavage because its no longer considered to be unicellular
Indeterminate Cleavage
Results in cells that are capable of becoming any cell in the organism
Determinate Cleavage
Results in cells that are committed to differentiating into a specific cell type
Determinate Cleavage
Results in cells that are committed to differentiating into a specific cell type
Morula
A solid mass of cells seen in early development that eventually becomes the blastula (blastocyst)
Blastula
A structure that contains blastocoel in its interior and contains trophoblasts and inner cell mass
Trophoblasts
Become placental structures
Inner Cell Mass
Becomes the developing organism
Placenta
Formed when the blastula implants into the endometrial lining
Placenta
Formed when the blastula implants into the endometrial lining; provides oxygen and nutrients to the fetus as well as removes carbon dioxide and waste products
Chorion
Contains chorionic villi which penetrates the endometrium and creates the interface between maternal and fetal blood
Yolk Sac
Supports the embryo before the placenta is established
Yolk Sac
Supports the embryo before the placenta is established
Allantois
Involved in early fluid exchange between the embryo and the yolk sac
Amnion
Inside the chorion which produces amniotic fluid
Amnion
Inside the chorion which produces amniotic fluid
Gastrulation
The cells of the blastula rearrange themselves and invaginate into the hollow ball so it creates an inner layer of cells and outer layer of cells and the cells between the two; forms Ecto, Meso and Endoderm
Archenteron
Formed with a blastopore at the end through the blastocoel; becomes the anus
Ectoderm
Becomes mouth, epidermis, hair, nails, anal canal, epithelia of the nose, lens of the eye and the adrenal medulla
Mesoderm
Becomes mostly the musculoskeletal, circulatory and excretory system; gonads; muscular and connective tissue layers of the digestive and respiratory systems; adrenal cortex
Mesoderm
Becomes mostly the musculoskeletal, circulatory and excretory system; gonads; muscular and connective tissue layers of the digestive and respiratory systems; adrenal cortex
Endoderm
Becomes the epithelial lining of the respiratory and digestive tracts and parts of the pancreas, thyroid, bladder and distal urinary tracts
Endoderm
Becomes the epithelial lining of the respiratory and digestive tracts and parts of the pancreas, thyroid, bladder and distal urinary tracts
Neurulation
Development of the nervous system that begins after the formation of the three germ layers
Notochord
Induces a group of overlying ectodermal cells to form neural folds surrounding a neural groove
Neural Tube
Forms from the fusing the neural folds and becomes the central nervous system (brain and spinal cord)
Neural Tube
Forms from the fusing the neural folds and becomes the central nervous system (brain and spinal cord)
Neural Crest Cells
Located at the tip of the neural folds and become the peripheral nervous system (sensory ganglia, autonomic ganglia, adrenal medulla and schwann cells)
Teratogens
Substances that interfere with development causes defects or death of the developing embryo; alcohol, certain drugs, viruses, bacteria and chemicals
Folic Acid Deficiency
Cause Neural Tube defects
Folic Acid Deficiency
Cause Neural Tube defects
Determination
Commitment of a specific cell lineage
What causes cellular determination?
Morphogens or uneven segregation of cellular material during mitosis
Morphogens
Promote development down a specific cell line
What does a cell need to have to respond to a specific morphogen?
Competency (ability to take up dna and become genetically transformed)
Differentiation
Changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line
Differentiation
Changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line
Stem Cells
Cells capable of developing into various cell types; classified by potency
Stem Cells
Cells capable of developing into various cell types; classified by potency
Totipotent Cells
Able to differentiate into all cell types, including three germ layers and placental structures
Totipotent Cells
Able to differentiate into all cell types, including three germ layers and placental structures
Pluripotent Cells
Able to differentiate into all three of the germ layers and their derivatives
Multipotent Cells
Able to differentiate only into a specific subset of cell types
Multipotent Cells
Able to differentiate only into a specific subset of cell types
Inducer
Releases factors to promote differentiation of a competent responder
Autocrine Signals
Act on the same cell that released the signal
Paracrine Signals
Act on cells in the local area
Juxtacrine Signals
Act through direct stimulation of the adjacent cells
Endocrine Signals
Act on distant tissues after traveling through the blood stream
Endocrine Signals
Act on distant tissues after traveling through the blood stream
Growth Factors
Peptides that promote differentiation and mitosis in certain tissues
Reciprocal Induction
When two tissues induce further differentiation in each other
Programmed Cell Death
Formation of apoptotic blebs that can subsequently be absorbed and digested by other cells; can be used to sculpt certain anatomical structures
Regenerative Capacity
Ability of an organism to regrow certain parts of the body; liver has high and heart has low
Senescence
Result of multiple molecular and metabolic processes; shortening of telomeres during cell division