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96 Cards in this Set

  • Front
  • Back
What are the major parts of an eukaryotic cell, and what are their functions?
Cell Membrane - controls what goes in and out
Golgi apparatus - controls import and export of proteins
Nucleus - brains of cell, stores DNA
Rough Endoplasmic Reticulum - has ribosomes for formation of DNA
Mitochondria - storehouse of energy
What are the two challenges imposed by fertilization?
- avoiding cross-species hybrids
- maintaining a diploid state
How are cross-species hybrids avoided?
- lock and key fit of ligand and receptor in sperm and egg cells
What is the fast way of blocking polyspermy?
- influx of Na ions changes electrical potential of oocyte plasma membrane

- prevents fusion of other sperm cells with plasma memrane

- activated in 0.1 seconds

- only lasts 1 minute
What is the slow way of blocking polyspermy?
- signalling pathway in oocyte makes calcium concentration in cytoplasm
What is triggered in the egg when sperm makes contact?
a signal transduction cascade
What are second messengers?
- small molecules that link two transducer proteins in a signalling pathway
What is the transducer in the egg cell cascade?
Phospholipase C
What are the second messengers n the egg cell cascade?
Inositol triphosphate (IP3), and Ca 2+
What are the features of a transduction pathway and where are they located?
Outside Cell - Ligand 9proteins, small molecules)

At Membrane - Receptor (proteins)

Cytoplasm - Transducer(s) (proteins, usually enzymes) and Second Messengers (small molecules, cofactors for enzymes)
What does the oocyte contribute to the zygote?
Haploid nucleus
Stored mRNAs
What does the sperm cell contribute to the Zygot?
Haploid nucleus
What is in the grey crescent of frog eggs?
Important cytoplasmic determinants
Which side does the grey crescent correspond to in amphibians?
The dorsal side of the embryo
What are chromosomes?
Continuous double helical stranded DNA, packaged with many proteins
Genes are spread ______ along the length of the chromosomes.
Is the coding region of a gene continuous?
Not usually
What is transcription and where in the cell does it occur?
The making of a strand of mRNA, in the nucleus
What is translation and where does it occur?
Taking mRNA and making proteins through a ribosome, in the cytoplasm
What is a blastomere?
a cell resulting from cleavage of a fertilized egg
What is a fate map for, and what are the three different levels they can be drawn at?
- shows ultimate fate of embyotic cells
- used to predict a cell's fate

levels: germ layers, tissues, cell types
What si the difference between cell fate and cell potential?
potential can only be revealed experimentally

Cell potential is broader than cell fate

Cell potential is lost as development proceeds
What is the order of development in an embryotic cell?
Totipotency, pluripotency, determined, differentiated
Define Totipotent
cell can be anything
Define pluripotent
cell can be one of a range of things, but not everything
What is mosaic development?
when individual blastomeres are determined early (by the 8 -cell stage)
What is regulative development?
blastomeres remain undetermined during cleavage
is genomic information lost during cell division?
No, it is just turned off
What are the three classes of protein-coding genes?
Metabolic, Structural, Regultory
What do metabolic protein-coding genes do?
- encode enzymes that participate in basic cell metabolism
(expressed in all cells)

- encode enzymes that have cell-specific functions
(restricted to certain cell types)
What do structural protein-coding genes do?
- encode structural proteins
(all cells, OR certain cell types)
What do regulatory protein-coding genes do?
- encode proteins that regulate the expression of other genes

Expressed as transcription factors (act directly on gene regulatory sequences) or signalling factors (act indirectly on genes, often at cell surface)
What is the defining property of stem cells?
What is a trophoblast?
the membrane that forms the wall of the blastocyst in early development
What is the cleavage stage?
a period of rapid cell division without growth of the embryo
What are cleavage patterns influenced by?
amount of yolk, and orientation of mitotic spindles
What is incomplete cleavage?
Multiple nuclei in one cell around the outside of cell, yolk in middle
What is a Drosophila?
A fly
Where are maternal effect genes expressed in Drosophila?
nurse cell in female ovary
What do maternal effect genes define?
anterior and posterior end of embryo
What are micoid and nanos? What do they do?
RNA binding proteins, bind to specific sequences in mRNA and regulate translation
What is gap gene expression?
When genes are expressed with gaps in between the coding regions
What is a blastodisc?
A flattened disc of cells formed because of the egg yold in reptile and bird eggs
What do cells in the organiser do?
express and secrete proteins that influence the behaviour (cell movement) and identities (commitment) of nearby cells
self-feedback loop
signal from one cell to neighbouring cell
what does a morphogen do?
reacts directly on a distant target cell, disrupts the relay mechanism f messaging through neighbouring cells
What are morphogens?
special signaling proteins that are involved in patterning embryos via gradient signalling
What are the properties of morphogens?
induce different cell fates at different concentrations

can act at a distance

have a direct effect on target cell
What are the two major cell arrangements? Describe them.
- regular cell shape
- tightly packed
- many cell-cell contacts
- simple or stacked sheets

- irregular shaped
- loosely packed
- few cell-cell contacts
What is somitogenesis?
the segmentation of a vertebrate body
What is a somite?
blocks of cells made from condensed notochord
What are the five processes that contribute to development? Describe them
- fixing the fate of an embryotic cell

- process by which different cells arise

- defining the orientation of the embryos and its tissues

- shaping of body and organs

- increase in size by cell division
animal vs vegetal pole?
animal pole
- small cells that divide quickly
- develops into embryo

vegetal pole
- large yolky cells that divide slowly
- develop into placenta
what is a trophoplast?
the membrane that forms the wall of the blastocyst in early development
What influences cleavage patterns?
- amount of yolk
- orientation of mitotic spindles
what is a homeobox?
a sequence of genes found in a particular genus
Conformers vs. regulators?
Conformers allow external change to influence internal change. Regulators maintain constant internal environment
Acclimatization vs Acclimation
Acclimatization is a response in the wild due to nature

Acclimation is a response induced by lab settings
What is an endotherm? What are some examples?
An endotherm generates heat from inside their own body through metabolic processes. Example: human
What is an ectotherm? Example?
An ectotherm needs heat from the environment. Example: reptiles
What is a homeotherm?
maintain a constant body temperature.
What is a poikilotherm?
An animal that has a fluctuating body temperature
What is a heterotherm?
an animal that regulates their body temp sometimes but not other times.
eg: hibernating mammals, small mammals and birds (shrew, hummingbird, bats), tuna and other related billfishes
Pros and Cons of Endothermy?
- sustain longer periods of activity
- evolve highly efficient and specialized enzymes
- can thrive on diverse environments

- requires more energy
- spend more time foraging, and less time on grown and reproduction
- food and water intake = high metabolic rate > high resp. rate + high level of water loss
Pros and Cons of Ectothermy?
- spend little energy on thermoregulation
- requires less food
- more energy used for growth and reproduction
- require less water
- small in size

- depends on environment for warmth
- limited range of suitable environments
- lower metabolic rate, less time spent in high intensity activity
What happens when endotherms cannot get enough energy to maintain body temp?
- hibernate
- torpor
- metabolic depression
- death
Bergmann's rule?
Mammals with wide distribution are larger in colder climates, making it so that they have more volume to SA
Why are elephants so large if they live at the equator?
Small SA to V helps prevent water loss

it takes more energy to heat a large mass of body

body acts as a buffer
How to elephants cool down?
When they get hot, they increase circulation to their ears
How do polar bears keep warm?
blubber - efficient at generating heat

white hairs reflect and transmit light - picks light up from sun

hairs trap air as an insulator
Why do endotherms have a much higher metabolism than ectotherms?
they have 5x the concentration of mitochondria in cells
Aside from shivering, what can endotherms do to generate heat?
- brown fat metabolism
- large concentration of mitochondria in brown fat
- non-coupling (don't make ATP, just release heat)
Who has the most brown fat?
young, lean women with normal blood sugar levels
Where is the body's thermostat?
In the hypothalamus
metabolic depression vs. torpor vs. hibernation
metabolic depression: drop a few degrees for a long period of time

torpor: drop 10-20 degrees nightly

hibernation: drop 30 degrees for an extended amount of time.
Do bears hibernate? Why are there no large hibernators?
reheating is too difficult
What is freeze avoidance?
- animals make "anti-freeze_ out of proteins and ion concentrated water
- make CRYOPROtECtANTS glycogens and sugars with lower freezing points
What is freeze tolerance?
- promote ice crystal formation outside of the cell
- BUT water leaves cell because the concentration of water inside the cell is greater than that outside the cell
What hormones are an active part of kidney function, and what do they do?
Aldosterone - from the adrenal gland, controls reabsorbtion of sodium into blood

Antidiuretic hormone (vassopression) - from the pituitary gland, controls absorbtion of water into the blood
Why does a higher salt intake lead to a higher blood pressure?
too much salt leads to water retention, which leads to an increase of blood volume, which leads to a higher blood pressure
How do diuretics work?
they inhibit the production of antidiuretic hormone
What are the two problems faced by the kangaroo rat, and how does it overcome them?
- maintain ionic balance in hot & dry environment
- has a high metabolic rate
- create higher concentration of urine
- nocturnal
- dry feces
- no water loss from breathing
How can it make a higher concentration of urine?
loop of Henle in a K rat is much longer
What are xerophytes?
plants that love dry environments
How to xerophytes prevent water loss?
- succulent form to store water
- heavy cuticle
- regulate opening of stomata
- deep tap roots
How does a cactus' stomata function?
open at night, take in CO2
close in the day when it's dry and hot
What are halophytes? What problems do they face?
plants that love salty environments

reduced water uptake due to saline conditions

toxic effect of specific ions on enzyme function

saline conditions inhibit growth
How to halophytes battle their environment?
- use salt regulators such as ion pumps
- store salt in vacuoles
Define entrainment
resting of circadian rhythm by environmental cues
What is "free running?"
Animal not bound to 24 hour cycle, clock runs on its natural cycle
a cycle that lasts less than a day
a cycle that runs with a period of more than one day
What part of the brain is responsible for maintaining the biological clock?
suprachiasmic nucleus
Why does it take so long to recover from jet-lag?
glands in all parts of body to not recover together (synchronised)
How does melatonin help with jet lag?
works while you are sleeping