darwin
define evolution - why is this important?
"Evolution is the process of change that has transformed life on Earth"
explains patterns in life and allows species to adapt and persist in a constantly changing environment
Homologous chromosomes are pairs of chromosomes that are similar in size, shape, and genetic content.
Humans have 23 sets of homologous chromosomes, making a total of 46
define cell differentiation
the process by which cells become specialized in structure and function
within the follicle of a fruit fly embryo, what is the cluster of diploid cells next to the egg called?
nurse cells
animals likely evolved how many million years ago?
500 mya
what is the process of natural selection?
Individuals who are best suited to their environment are
more likely to survive and reproduce
Over time, more individuals in a population will have the
advantageous traits
independent assortment - metaphase 1
crossing over - prophase 1
random fertilization - does not happen in meiosis
what are the three things a zygote must undergo to transform into an adult?
cell division, cell differentiation, and morphogenesis
what are nurse cells? what function do they serve?
Nurse cells set up patterning in the egg before fertilization ever happens!
they contain maternal effect genes that encode cytoplasmic determinants
which two groups of animals are thought to have evolved first?
sponges and cnidarians!
give an example of a correlation between structure and function
(hint: can be within a single organism or seen in how two organisms interact!)
between organisms: a plant may shape its flowers in a specific way to maximize pollination
explain the pros and cons of sexual reproduction vs asexual reproduction
sexual reproduction
- allows genetic variation! guarunteed specie persistence through time
- metabolically expensive to birth and raise offspring, potentially fatal mating seasons
asexual reproduction
- not expensive, only requires one parent organism to produce an offspring
- does not allow for genetic variation in a specie
explain the difference between cell determination and cell differentiation
Determination commits a cell irreversibly to its final fate - PRECEDES differentiation, the process by which a cell attains its determined fate
regulatory genes vs structural genes
Define a true animal. Do sponges fit into this category?
true animals are those with the typical characteristics of an animal: nervous tissue, GI cavity/tract, etc...
sponges are NOT true animals
Describe what Darwin meant in the phrase "descent with modification." what mechanism is behind this?
mechanism behind this = natural selection
explain the difference between the centromere of a chromosome and a chiasmata
A centromere is the region in the middle of two sister chromatids where they join. A chiasmata is the region where two non-sister chromatids are joined.
what are cytoplasmic determinates?
name the maternal effect gene that sets up the anterior half of a fruit fly - how exactly does it do this?
Bicoid gene
Embryos contain high concentrations of bicoid mRNA on one end – the same end of the nurse cells. After the egg is fertilized, the mRNA is translated into bicoid protein, which diffuses from the anterior end, forming a gradient. This gradient establishes the head/thorax/abdomen sections
sponges are what type of feeders? which cell in their body plan allows for this?
- water is drawn into the body via pores, and flagellated Choanocytes beat their tails to generate a water current. this water current delivers any edible substances in the water to the sponge tissue for digestion
what were darwin's three observations that supported his theory of evolution?
1. Individuals in a population vary in their traits, many of which are heritable
2. More offspring are produced than survive, and competition is inevitable
3. Species generally suit their environment
if two cells were to undergo JUST independent assortment, and no crossing over occurs, how many genetically unique gametes can be formed?
4
if most cells in the human body contain the exact same genetic code, how are different cell types, tissues, and organs formed?
Different genes are turned on in different cells via induction, which determines their fate.
are hox genes, or homeotic genes, regulatory or structural?
regulatory
which cells in sponge walls play a role in both digestion and structure?
amoebocytes