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darwin

100

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

200

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

300

give an example of a correlation between structure and function

(hint: can be within a single organism or seen in how two organisms interact!)

within a single organism: hummingbird's wings are designed to support rapid movement in an atypical figure-eight shape

between organisms: a plant may shape its flowers in a specific way to maximize pollination

400

Describe what Darwin meant in the phrase "descent with modification." what mechanism is behind this?

descent with modification describes the process of species adapting to their environment - organisms show evidence of descent through time with modified traits compared to their common ancestor

mechanism behind this = natural selection 

500

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

meiosis

100

what does it mean when two chromosomes are homologous? how many homologous chromosomes does a typical human have?

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

200

list the three types of genetic variation and the stages in meiosis in which they occur

independent assortment - metaphase 1

crossing over - prophase 1

random fertilization - does not happen in meiosis

300

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 

400

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.

500

if two cells were to undergo JUST independent assortment, and no crossing over occurs, how many genetically unique gametes can be formed?

4

embryodevelopment

100

define cell differentiation

the process by which cells become specialized in structure and function

200

what are the three things a zygote must undergo to transform into an adult?

cell division, cell differentiation, and morphogenesis

300

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

400

what are cytoplasmic determinates?

• Maternal substances in the egg that influence early development
• As the zygote divides by mitosis, the resulting cells contain different cytoplasmic determinants, which lead to different gene expression

500

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.

• Induction = signal molecules from embryonic cells cause transcriptional changes in nearby target cells

fruit flies

100

within the follicle of a fruit fly embryo, what is the cluster of diploid cells next to the egg called?

nurse cells

200

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 

300

regulatory genes vs structural genes

• Structural genes dictate where a limb or wing will be placed. they can be switched on/off based on where in the body they are located
• Regulatory genes are the switches that dictate where the structural genes are expressed

400

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

500

are hox genes, or homeotic genes, regulatory or structural?

regulatory

animals!

100

animals likely evolved how many million years ago?

500 mya

200

which two groups of animals are thought to have evolved first?

sponges and cnidarians!

300

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

400

sponges are what type of feeders? which cell in their body plan allows for this?

- suspension feeders

- 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

500

which cells in sponge walls play a role in both digestion and structure?

amoebocytes