Bio: Ch 2, 6 Flashcards
diploid (2n) cells have…
two copies of each chromosome
haploid (n) cells have…
one copy of each chromosome
cell cycle stages
- interphase
- G1
- S
- G2
- M
- G0
interphase
inlcudes G1, S, G2
DNA is uncoiled in the form of chromatin
longest part of cell cycle, cells spend 90% of their time in this phase
cell cycle
phases during which a cell grows, synthesizes DNA, and divides
G0 phase
cell is living and carrying out its functions
without preparing for division
G1 phase
presynthetic gap
cells create organelles for energy and protein production, and increase their size
need to pass G1 checkpoint before going to S phase
G1 check point/restriction point
need to pass into S phase
DNA checked for quality
if fails: cell cycle arrests until DNA is repaired
S phase
synthesis
DNA is replicated (each daughter cell will have identical copies)
each chromosome will have two identical chromatids bound by centromere
chromatid is composed of
complete double stranded molecule of DNA
sister chromatids
identical copies of the same DNA held together at the centromere
G2 phase
postsynthetic gap
further cell growth and replication of organelles in prep for mitosis
checkpoint to enter M phase
G2 checkpoint
must pass to enter M phase
checks that there’s enough organelles and cytoplasm for two daughter cells
checks that DNA replication proceeded correction (to avoid passing on error to daughter cell)
M phase
mitosis
mitosis and cytokinesis occur
cytokinesis
occurs at end of telophase
splitting of the cytoplasm and organelles between the two daughter cells
p53
plays important role in the two major checkpoints of cell cycle (G1 and G2 checkpoints)
cyclins and cyclin dependent kinases (CDK) during cell cycle
rise and fall
cyclins bind to CDKs, phosphorylating and activating transcription factors for the next stage
transcription factors during cell cycle
promote transcription of genes required for the next stage of cell cycle
in order to be activated, CDKs require…
presence of the right cyclins
cancer
occurs when cell cycle control becomes deranged, allowing damaged cells to under mitosis without regard to quality or quantity of the new cells produced
cancerous cells may begin to produce factors that allow them to delocalize and invade adjacent tissues or metastasize elsewhere
common mutations found in cancer and what happens
mutation of the gene that produces p53, called TP53
cell cycle is not stopped to repair damaged DNA –> allows mutations to accumulate, resulting in cancerous cell that divides continuously
mitosis
two identical daughter cells are created from a single cell
only occurs in somatic cells
somatic cells
cells that are not involved in sexual reproduction
mitosis phases
- prophase
- metaphase
- anaphase
- telophase
prophase
1
- chromosomes condense
- spindle apparatus begins to form
- nuclear membrane dissolves
- nucleoli disappear
- centrioles migrate to opposite sides of the cell
- kinetochore of each chromosome is contacted by spindle fiber
kinetochore
protein structures located on centromeres that serve as attachment points for specific fibers of the spindle apparatus
appear at centrosome during prophase
metaphase
2
chromosomes line up along metaphase plate (done by kinetochores)
anaphase
3
sister chromatids are separated and pulled to opposite poles
telophase
4
- nuclear membrane reforms
- spindle apparatus disappears
- cytosol and organelles split between two daughter cells through cytokinesis
gametes
sex cells
gametocytes
germ cells
meiosis
produces up to 4 nonidentical haploid sex cells (gametes)
occurs in gametocytes
has one round of replication and two rounds of division (reductional and equational divisions)
meiosis I
reductional division
results in homologous chromosomes being separated, generating haploid daughter cells
homologues
related chromosomes of opposite parental origin
meiosis II
equational division
results in the separation of sister chromatids without a change in ploidy
(like mitosis)
prophase I
meiosis
- same as in prophase of mitosis EXCEPT:
- synapsis and crossing over
synapsis
homologous chromosomes come together and intertwine
during prophase I
tetrad
a synaptic pair that contains 4 chromatidds
synaptonemal complex
group of proteins that hold together homologous chromosomes during synapsis
chiasma
point of contact between two chromatids during synapsis where DNA is exchanged
crossing over
exchanges genetic material between one chromatid and material from a chromatid from the homologous chromosome
mendel’s second law of independent assortment
during prophase I of meiosis
mendel’s second law
of independent assortment
the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
metaphase I
meiosis
homologous chromosomes line up on opposite sides of the metaphase plate
disjunction
chromosome of paternal origin separates from its homologue of maternal origin
during anaphase I of meiosis
accounts for mendel’s first law of segregation
segregation
separation of two homologous chromosomes
during anaphase I
anaphase I
meiosis
homologous chromosomes are pulled to opposite poles (disjunction, segregation)
mendel’s first law of segregation
mendel’s first law
of segregation
during gamete formation, the two alleles at a gene locus segregate from each other; each gamete has an equal probability of containing either allele
during anaphase I
interkinesis
chromosomes partially uncoil
may occur between telophase I and prophase II
telophase I
meiosis
chromosomes may or may not fully decondense
cytokinesis
cell may enter interkinesis
mitosis vs meiosis
ploidy
mitosis: 2n –> 2n
meiosis: 2n –> n
mitosis vs meiosis
homologous chromosomes
mitosis: homologous chromosomes do not pair
meiosis: homologous chromosomes align on opposite sides of metaphase plate
biological sex is determined by
23rd pair of chomosomes in humans
X chromosome
carries sizeable amount of genetic information
sex linked disorder
males vs females
can be caused by mutations of X linked genes
males will express sex-linked orders, even if they only have one recessive allele
women with only one copy of the affected allele are carriers
Y chromosome
carries little genetic info
contains SRY (sex determining region Y) gene
SRY gene
causes the gonads to differentiate into testes
pathway of sperm through male reproductive system
SEVE(N) UP
- seminiferous tubules
- epididymis
- vas deferens
- ejaculatory duct
- (nothing)
- urethra
- penis
seminal vesicles
contribute fructose to nourish sperm and produce alkaline fluid
seminiferous tubules
where sperm developes
sertoli cells
nourish the sperm
interstitial cells of leydig
secrete testosterone and other male sex hormones (androgens)
scrotum
where testes are located
hangs outside the abdominal cavity
has temp 2-3 C lower than rest of body
epididymis
store sperm until ejaculation
prostate gland
produces alkaline fluid that give the semen mildly alkaline properties so the sperm can survive in the relative acidity of the female reproductive tract
bulbourethral glands
produce clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
semen
sperm and seminal fluid
spermatogenesis
four haploid sperm are produced from a spermatogonium
occurs in seminiferous tubules
spermatogonia
male diploid stem cells
spermatogenesis steps
- after S stage: primary spermatocytes
- after meiosis I: secondary spermatocytes
- after meiosis II: spermatids
- after maturation: spermatozoa
spermatogenesis
what are germ cells called after S stage?
primary spermatocytes
spermatogenesis
what are germ cells called after meiosis I?
secondary spermatocytes
spermatogenesis
what are germ cells called after meiosis II?
spermatids
spermatogenesis
what are germ cells called after maturation?
spermatozoa
sperm structure
head, midpiece, flagellum
sperm structure
head
contains genetic material
covered with acrosome
acrosome
modified golgi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum
sperm structure
midpiece
generates ATP from fructose and contains many mitochondria
sperm structure
flagellum
promotes motility
ova
eggs
ova are produced in
follicles in the ovaries
ovaries
produce estrogen and progesterone
follicles
multilayered sacs that contain, nourish, and protect immature ova
peritoneal sac
lines th eabdominal cavity
fallopian tube/oviduct
lined with cilia to propel egg forward
uterus
site of fetal development
vulva
external female anatomy
vaginal canal
lies below cervix
site where sperm are deposited during intercourse
site of natural childbirth
oogenesis
one haploid ovum and a variable number of polar bodies are formed from oogonium
oogenesis steps
- at birth, all oogonia have undergone replication and are arrested in prophase I –> primary oocyte
- ovulated egg each month is arrester in metaphase II –> secondary oocyte
- if oocyte is fertilized, it will complete meiosis II –> ovum
- haploid pronuclei of sperm and ovum join, creating diploid zygote
polar body
cell during oogenesis that receives very little cytoplasm and organelles during cytokinesis
oocyte structure
surrounded by zona pellucida and corona radiata
zona pellucida
acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding
corona radiata
layer of cells that adhered to the oocyte during ovulation
mature ovum
very large cell consisting of large quantities of cytoplasm and organells
contributes nearly everything to zygote
how is zygote formed
once meiosis II of ovum is completed, haploid pronuclei of sperm and ovum join, creating diploid zygote
sexual development once puberty hits
hypothalamus stops restricting the production of GnRH –> anterior pituitary makes and releases FSH and LH –> trigger production of other sex hormones
sexual development in males
FSH
stimulates sertoli cells and triggers spermatogenesis
sexual development in males
LH
causes the interstitial cells to produce testosterone
testosterone
responsible for the maintenance and development of male reproductive system and male secondary sex characteristics
male secondary sex characteristics
facial and axillary hair
depending of voice
increased bone and muscle mass
sexual development in females
FSH
stimulates development of ovarial follicles
sexual development in females
LH
causes ovulation
sexual development in femals
FSH and LH
stimulate production of estrogens and progesterone
sexual development in females
estrogen
secreted in response to FSH
development and maintenance of female reproductive system and female secondary sex characteristics
female secondary sex characteristics
breast growth, widening of hips, changes in fat distribution
estrogen in embryo
stimulate development of reproductive tract
estrogen in adults
lead to thickening of lining of uterus each month in perp for implantation of a zygote
endometrium
lining of uterus
sexual development in females
progesterone
secreted by corpus luteum in response to LH
development and maintenance of endometrium (not initial thickening)
corpus luteum
remains of the ovarian follicle following ovulation
menstrual cycle
periodic growth and shedding of endometrial lining
menstrual cycle steps
+ graph**
- follicular phase
- ovulation
- luteal phase
- menstruation (if no fertilization)
follicular phase
follicles mature
- mentrual flow
- GnRH secretion stimulates FSH and LH secretion –> follicle development
- estrogen release –> vasicularization and glandularization of decidua
ovulation
release of ovum from ovary into abdominal cavity
- stimulated by LH surge
- LH surge triggered when estrogen levels reach threshold and switch from negative to positive feedback effects
luteal phase
- LH causes ruptured follicle to become corpus luteum
- corpus luteum secretes progesterone –> maintains uterine lining
- high estrogen and progesterone levels cause neg feedback on GnRH, LH, and FSH
menstruation
occurs if no fertilization
estrogen and progesterone levels drop –> endometrial lining comes off –> block on GnRH production removed –> FSH and LH levels begin to rise again
menstrual cycle
what happens when fertilization occurs
blastula implants in uterine lining and produces human chorionic gonadotropin (hCG) –> maintain corpus luteum
near end of 1st trimester, hCG levels drop as placenta takes over progesterone production
menopause
occurs when ovaries stop producing estrogen and progesterone
- usually between ages 45-55
- menstruation stops
- FSH and LH levels rise
- flushing, hot flashes, bloating, headaches, irritability
Interphase has three main phases. Compare these three.
G1 (Growth Phase 1) is the longest phase in which a cell grows, making more organelles and proteins.
S Phase (Synthesis Phase) occurs when the cell is replicating its DNA.
G2 (Growth Phase 2) is when cells prepare for Mitosis by editing DNA for errors/mutations, making microtubules, etc.
Sometimes a cell will go into G₀ instead of continuing into S Phase. What is G₀ characterized by? Give an example of a cell that might enter G₀.
A cell that enters G₀ is essentially done dividing for the rest of its lifespan. A Neuron is an example of a cell that enters G₀.
CRB Compare what is being checked for at each of the 2 major checkpoints.
Before the cell enters S phase, the cell wants to make sure its DNA has no mutations, irregularities, mismatches, etc.
During G2, the cell wants to make sure that there is enough organelles, cytoplasm, etc. for two separate daughter cells to survive. The replication that occurred in S phase is also double-checked here
True or False? CDK’s are always present in the cell.
True. CDK’s are always present in the cell. It is the production of the Cyclin proteins that is regulated. Different Cyclin proteins are produced at different times.
A single Chromosome replicates. How many chromosomes result? Chromatids?
Two sister chromatids attached at the centromere count as one chromosome. Once the sister chromatids detach, then they are considered two distinct chromosomes.
When the cell is in G1, in what state is its DNA?
(A) The densely compacted Chromatids
(B) The less condensed Chromatids
(C) The densely compacted Chromatin
(D) The less condensed Chromatin
(D) The less condensed Chromatin
Chromatin is less condensed than Chromatid. During interphase, DNA is not very condensed, and is considered Chromatin.
What is happening with the Centrosomes during each phase of Mitosis?
(1) Prophase
(2) Metaphase
(3) Anaphase
(4) Telophase
(1) Prophase - Centrosomes move toward the poles of the cell.
(2) Metaphase - Centrosomes are now at the poles of the cell. The microtubules are attached to the chromosomes lined up in the center of the cell.
(3) Anaphase - The microtubules pull the chromosomes apart from each other to opposite poles of the cell.
(4) Telophase - A single Centrosome (with its centriole pair) ends up in each cell.
CRB True or false? Crossing over can happen multiple times in the same Tetrad, and can unlink previously-linked genes.
True. Crossing over can happen multiple times in the same Tetrad, and can unlink previously-linked genes.
This is called Recombination.
True or False: Meiosis I produces diploid cells, and meiosis II produces haploid cells.
False. Meiosis I produces HAPLOID cells, and meiosis II produces haploid cells.
A Nondisjunction event is when homologous pairs do not separate and are not pulled to separate poles of the cell. When could a nondisjunction event affect the number of chromosomes in the daughter cell or gamete?
I. Mitosis
II. Meiosis I
III. Meiosis II
(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III
(D) I, II and III
nares
where air enters
vibrissae
nasal hairs
larynx contains…
two vocal cords (glottis)
alveoli
small sacs that interface with pulmonary capillaries, allowing gases to diffuse across a one cell thick membrane
where gas exchange occurs
psurfactant
coats alveoli
detergent that lowers surface tension and prevents alveolus from collapsing on itself
air -> lungs pathway
nares > nasal cavity > pharynx > larynx > trachaea > bronchi > bronchioles > alveoli
pleurae
cover lungs and line chest wall
visceral pleura
lies adjacent to lung itself
parietal pleura
lines chest wall
intrapleural space
lies between visceral and parietal pleura
contains a thin layer of fluid that lubricates the two pleural surfaces
diaphragm
thin skeletal muscle that helps to create the pressure differential required for breathing
inhalation steps
negative pressure breathing
- diaphragm and external intercostal muscles expand thoracic cavity -> inc volume of intrapleural space -> dec intrapleural pressure
- this pressure differential expands the lungs -> dec pressure within -> draw in air from environment
inhalation is a ___ process
active
exhalation is a __ process
passive or active
passive exhalation steps
- muscles of inspiration relax
- elastic recoil of the lungs allows chest cavity to dec volume –> intrapleural pressure
- air pushed out
active exhalation steps
internal intercostal muscles and abdominal muscles used to forcible decrease volume of thoracic cavity -> inc intrapleural pressure -> pushes air out
intrathoracic volume
volume of chest cavity
spirometer
used to measure lung capacity and volume
total lung capacity (TLC)
max volume of air in the lung when one inhales completely
residual volume (RV)
volume of air remaining in the lungs when one exhales completely
vital capacity (VC)
difference between the min and max volume of air in lungs
tidal volume (TV)
volume of air inhaled or exhaled in a normal breath
expiratory reserve volume (ERV)
volume of additional air that can be forcibly exhaled after a normal exhalation
inspiratory reserve volume (IRV)
volume of additional air that can be forcibly inhaled after a normal inhalation
ventilation center
collection of neurons in medulla oblongata where ventilation is regulated
chemoreceptors
respond to CO2 concentrations
inc or dec respiratory rate dependent on CO2 conc in blood
what happens to respiratory rate when high conc of CO2 in blood
increases
hypercarbia/hypercapnia
high conc of CO2 in blood
what happens to respiratory rate when low conc of O2 in blood
increase
hypoxemia
low o2 conc in blood
what part of brain consciously controls ventilation when wanted?
cerebrum
what happens to respiratory rate when low conc of CO2 in blood?
dec to raise CO2 levels
gas exchange with lungs
simple diffusion across conc gradients
deoxygenated blood with a high co2 conc is brought to the lungs via the…
pulmonary arteries
oxygenated blood with low co2 conc leaves the lungs via the…
pulmonary veins
pulmonary arters originate from
right ventricle of heart
pulmonary arteries
bring deozygenated blood with high co2 conc to lungh=s
pulmonary veins
bring oxygenated blood with low co2 conc away from the lungs
thermoregulation and respiratory system
how to dissipate thermal energy
capillaries expand, more blood passes through vessels
acidemia
low blood pH
alkalemia
high blood pH
mucociliary escalator
internal airways have mucus that trap invaders
underlying cilia propel the mucus up the respiratory tract to oral cavity where it can be expelled or swallowed
how respiratory system is protected from potential pathogens
- vibrissae, mucus, mucociliary escalator –> filter and trap invaders
- lysozyme in nasal cavity and saliva
- macrophages
- mucoseal surfaces covered with IgA antibodies
- mast cells
lysozyme in respiratory system
attacks peptidoglycal walls of gram positive bacteria
how is respiratory system involved in pH control
bicarbonate buffer system
bicarbonate buffer system
blood pH decreases
respiration rate increases to compensate by blowing off CO2
left shift in buffer eq -> reduces hydrogen ion conc
bicarbonate buffer system
blood pH increases
respiration rate decreases to compensate by trapping co2
causes right shift in buffer eq -> inc hydrogen ion conc
The right lung has ____ lobes, and the left lung has _____ lobes.
(A) 3, 3
(B) 3, 2
(C) 2, 2
(D) 2, 3
(B) 3, 2
The right lung has 3 lobes. The left lung has 2 lobes.
Between the Internal and External Intercostals, which are associated with Inhalation, and which are associated with Exhalation?
The Internal Intercostal muscles contracting will pull down on the rib cage, decreasing the intrathoracic volume and causing exhalation.
The External Intercostal Muscles contracting will pull the rib cage and expand the intrathoracic volume, causing inhalation.
CRB One of the biggest dangers for premature babies is that their lungs cannot produce enough surfactant to be able to breath effectively on their own. Explain the key role of Surfactant in respiration.
Surfactant is a detergent that coats the alveoli, decreasing surface tension and making it easier to inflate the alveoli. Without surfactant, alveoli have a greater chance at collapsing.
Oxygen is 26x less soluble in water than Carbon Dioxide. Why is this the case?
Carbon Dioxide can form carbonic acid (H2CO3), which will auto-dissociate into H+ and bicarbonate, which is very soluble in water.
Oxygen cannot form a charged ion in a similar fashion.
CRB True or false? Based on the previous notecard, Hyperventilation can be called Respiratory Alkalosis (trying to make the blood more basic), and Hypoventilation can be called Respiratory Acidosis.
True. Based on the previous notecard, Hyperventilation can be called Respiratory Alkalosis (trying to make the blood more basic), and Hypoventilation can be called Respiratory Acidosis.
Respiration involves the diffusion of gasses, oxygen and carbon dioxide, across plasma membranes. Because respiration is passive, the difference in concentrations drives diffusion. Which of the following can increase diffusion?
I. Increased distance
II. Decreased molecular weight of molecules
III. Increased pressure
(A) I and II only
(B) III only
(C) II and III only
(D) I only
(C) II and III only
To increase the rate of diffusion:
- DECREASE the distance
- Decrease the MW of the molecules
- Increase the pressure
- Increase the area
Which of the following conditions would impair gas exchange and cause hypoxia?
I. Scarring of the alveoli
II. Limiting Ventilation to the Lungs
III. Limiting Perfusion to the lungs
(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III
(D) I, II and III
Each of the following conditions could impair gas exchange and cause hypoxia:
I. Scarring of the alveoli
II. Limiting Ventilation to the Lungs
III. Limiting Perfusion to the lungs
At rest, humans will typically breathe in and out about 5 liters of air per minute. When exercising, this rate may increase to 50L/min. Why is this important in terms of energy generation? Why is this important in terms of thermoregulation?
This increased breathe rate is essential for generating more energy via aerobic respiration.
This increased breathe rate is also useful in preventing overheating. With each breath, cold air enters and hot air leaves the body.
Which of the following does Vital Capacity NOT include?
(A) Residual Volume
(B) Tidal Volume
(C) Expiratory Reserve Volume
(D) Inspiratory Reserve Volume
(A) Residual Volume
Vital Capacity includes all of the volume that can be consciously changed, including Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume.
