Flashcards in Midterm 2 Deck (140):
A set of chromosomes, one maternal and one paternal that pair up during meiosis. They contain the same genes but not necessarily the same alleles
The cell prepares for cell division, DNA is synthesized
Nuclear envelope disappears. One kinetochore forms, microtubules grow from centromere
Chromosomes line up side-by-side in the center of the cell
The cell divides into two 2n cells
Chromatids line up
The cell divides into two haploid cells
How does meiosis differ from mitosis
Meiosis results in four nuclei by two divisions that are haploid. The nuclei in meiosis are not identical after division. The chromatids are arranged side-by-side, not up and down and there can be crossover.
In humans, what is the difference between spermatogenesis and oogenesis?
Spermatogenesis creates four sperm, oogenesis creates 1 ovum and three polar bodies
What is the difference between a somatic cell and a gamete?
A somatic cell is diploid, a gamete is haploid.
Law of segregation
1)alternative versions of genes account for variations in inherited traits-alleles
2)an organism inherits two copies of a gene, one from each parent
3)the dominant allele determines appearance
4)the two alleles for a characteristic end up in different gametes
Law of independent assortment
Each pair of genes sort independently into gametes, so you just account for all possibilities
Non-sex chromosomes, we have 22
Carried on the x and y chromosom s
Structure that carries genes, we have 23. Each code for different traits
Nucleic acids that condense to form a chromosome
Network of tubules that separates chromatids
One of the two strands that a chromosome divides into
The organelle that contains the centrioles
The part of a chromosome that links sister chromatids
The number of copies of homologous chromosomes
A complete set
2 complete sets
The presence of an abnormal number of chromosomes in a cell
A fertilized ovum, a diploid cell resulting from the fusion of two haploid gametes
One set of maternal and one set of paternal chromosomes that pair up during meiosis
Takes place during prophase 1, the matching up of two homologous chromosomes
Because the homologous chromosomes are so close, they exchange some information
The failure of homologous chromosomes to separate properly during cell division that results in abnormal chromosome numbers(aneuploidy) ex: Down syndrome
The primary set of parents crossed
First filial generation
Second filial generation
Offspring of offspring
The gene that is expressed
The gene that has to be homozygous to be expressed
The trait expressed
The alleles present in the offspring
AA or aa, the same alleles
Aa, different alleles
Diagram that shows the appearance of a particular gene
Conditions that would have led to formation of the first unicellular life form
The environment was reducing so organic molecules could spontaneously form. Phospholipids formed proto-cells
19th century scientists conclusions about the nature of life forms and our current atmosphere
Our current atmosphere is oxidizing, 4.5-3.5 billion years ago it was reducing so organic molecules could form. Life forms are carbon-based. Life forms represent order, so they are maintained at the expense of energy productions. Life comes from life
Haldane and oparin
Proposed the original environment was reducing not oxidizing so complex molecules are formed spontaneously. It is intrinsic to the nature of carbon that it will form polymers
Reducing vs. oxidizing environment
A reducing environment allows complex molecules to form spontaneously, oxidizing is towards break down b/c free radicals
What features make the earth a suitable place for life forms?
Water, reducing atmosphere, distance from sun, mass
What was the purpose of the Miller/Urey experiment?
In a reducing environment, they made glucose and amino acids. They showed the abiotic production of organic molecules
What is the relationship between carbonaceous chondrites and the abiotic production of organic molecules
Carbonaceous chondrites spontaneously form organic molecules if energy is added
Devoid of life
Evidence for life
Stromatolites form from bacteria and they date back 3 billion years ago
Unable to create its own food, must rely on consumption of other organisms
Photosynthetic, self-sustainable, creates its own food
How does the photosynthetic mechanism in green/sulfur bacteria differ from blue/green bacteria
Green sulfur produces glucose and sulfur, blue/green bacteria produces oxygen and water
What were the ramifications of blue/green bacteria developing photosynthesis
The environment shifted to oxidizing and metals soaked up oxygen
What do deposits of red belt reveal to you?
There was oxygen and metal ions in the oxygen 3 billion years ago
What were the ramifications of the atmosphere shifting to oxidizing for prokaryotes?
There was mass extinction, anaerobic organisms either died or moved to anaerobic environments. Prokaryotes with electron transport chains used oxygen as a final electron acceptor and could survive
Proto-eukaryotes used endosymbiosis to eat a proto-mitochondrion and form an Enzo-symbionts that can live in a o2 toxic environment
Selective advantage of endosymbiosis for the endosymbiont
Can detoxify oxygen and run ATP synthase
Prokaryote with bigger ribosomes and RNA is closer to us vs. archaea
Membrane bound sub compartments, unicellular or multicellular
Unicellular eukaryotes, including autotrophs, heterotrophs, highly sophisticated organelles
Single-felled or multicellular, non-photosynthetic heterotrophs, have a cell wall, but primarily chitin. Saprophytes decompose organic matter
About 1 billion years ago
Features that unite all organisms in kingdom plantae
Multicellular eukaryotes, aerobic, use glucose as primary metabolite, photosynthetic autotrophs, all cells surrounded by a cell wall made of cellulose, aquatic or terrestrial, sedentary
Features of plant eukaryotes cells
Rod shaped dna, circular DNA in mitochondria and chloroplast, cell wall, plasma membrane, cytoplasm, nucleus with double membrane, nucleolus, ER, golgi, mitochondrion, chloroplast, lysosomes, large vacuole
Where would you find DNA in plant cells
In the chloroplast, mitochondria, and nucleus
Where would you find ribosomes?
On the rough ER, cytoplasm, chloroplasts, mitochondria
What types of ribosomes are there?
Free ribosomes and attached ribosomes
What are the features of the plant cell wall?
They have rivets to connect to other cell walls and extra cellular fluid
Vascular vs. no vascular plants
Vascular plants have vascular systems such as xylem and phloem, nonvascukar plants do not have these systems
Spores vs. gametes
Gamete is a sex cell with haploid, spore is a full set of chromosomes and can germinate to become a full plant
Why does H2O move into a bryophyte cell?
How do fades enter a bryophyte cell?
Is there a vascular network in bryophytes for moving water, gases, and nutrients between cells?
No just diffusion
Features of the cuticle of vascular plants
Waxy covering in the surface of the cell. The cuticle blocks the diffusion of H2O and gases into and out of the plant. The sonata is a small opening for gas exchange and water movement into and out of the plant
On a stomata, what are guard cells?
The guard cells control gas exchange from the stoma. Between there is a stoma pore
How does a stem on a fern differ from the trunk of a gymnosperm? What features do these structures share in common?
The trunk is non photosynthetic, the outer covering is dead cells called bark: gymnosperms have extensive root systems, ferns do not. Leaves of ferns are not shed
What is fruit
Organism able to produce its own food through photosynthesis
Organelles where photosynthesis occurs
Green pigment found in plants that allows plants to absorb energy from light
The major structural component of cell walls
Range of organisms that lack stomata, xylem, and phloem so non-vascular, moss and bryophytes, algarrobos
Have xylem and phloem, CERN's, misses, conifers, angiosperms, gymnosperms
One way only, carries water and minerals in vascular plants
Two-way flow, carries water and food
Alternation of generations
Process of reproduction in plants
Organ of gametophyte that contains the ovum, haploid
Has both male and female sexes
Ovules are contained here in gymnosperms
Cone containing pollen
Structure that produces mega spores
Single cells that pollen is composed of
Allows seed to be airborne
Protects the flower in bud and supports
Modified colored leaves that attract bees to carry pollen
The female organs of the flower
Contains ovum in flower
Slender tube that connects stigma to ovary
Receptive tip that receives pollen and where pollen grain germinates
The part of the stamen that contains the pollen
The smaller type of spore produced by ferns
One of the two nuclei that eventually fuse to form endosperm
Contained in ovule
Goes through ovary to get to egg
Two sperms travel down style, one fuses with an egg and the other with polar nuclei
Fertilized egg divides to form and embryo which is kept in seed until the right conditions arise
Nutritive tissue that can provide food for the developing plant
There is a hierarchical way to nature, higher and lower animals
Is any species more evolved than others?
Baron Cuvier four groups
Radiata-circular animals, articulate-segmented animals, mollusca-animals with a shell and brain, vertebrate-bony skeleton, muscular hear, red blood
Inheritance of acquired characteristics, individual evolution. Ex: giraffes have long necks because they stretch them
Who originally organized things as trees
What is a phylum?
A group of animals that have a common body plan
Vertabrates, notochord, hollow nerve chord, pharyngeal gill slits
How many phylums of animals are there?
What is an animal?
Animals are eukaryotes, lack a cell wall, diploid body form, multicellular, mobile, use sexual reproductions, heterotrophs with internal cavity
Closest known single celled relatives of animals
The female and male have the same size
What is special about bedfellows rodillera?
The have lost sex
How do females reproduce?
Parthogenesis. Males have not been observed
Developmental sequence of most animals
Zygote, eight cell stage, blastula, blastocoel, gastrilation
What are the three germ layers?
Ectoderm, mesoderm, endoderm
What is osmoheterotrophy?
Directly from environment into cells
What does it mean to be phagocytic?
Cells that ingest foreign particles
What does it mean to be a typical animal
The cell membrane contains cholesterol, neurons and muscles are unique to animals, epithelial tissues are in all animals, unique cell junctions
Genomic features of animals
Mitochondrial genomes are greatly reduced
Two supergroups of animals
Non-bilateral and bilateral
Germ layers of non-bilaterians vs. bilaterians
Non-bilaterians have two embryonic germ layers, bilaterians have three embryonic germ levels
Coelomates vs. pseudocoelomates vs. acoelomates
Coelomates-fluid filled cavity, pseudocoelomates-reduced fluid filled cavity, acoelomates-no body cavity
Four major groups of bilaterians
Xenacoelomorpha(some worms), spiralia/lophotrochozoa(other worms, molluscs, moss animals), ecdysozoa(more worms, insects, crabs, spiders), deuterostomia(even more worms, starfish, urchins, tunicates, vertebrates)
Which organisms are in phylum porifera?
What are the characteristics of phylum porifera?
Marine and freshwater, sexual and asexual reproduction, assymetrical, vascular system, fiber skeleton made of spongin
What is phylum Ctenophora?
Comb jellies that eat plankton, have rotational symmetry
What are defining characteristics of phylum placozoa?
They have no symmetry, dorsal central polarity, no muscles, nerves or gut, asexually reproductive, move by ciliary locomotion
Main characteristics of phylum Cnidaria(anemones, corals, and jellyfish)
Mostly radial symmetrical, incomplete gut, indirect sexual development, asexual development by budding, nematocysts, have neurons and muscles
Incomplete guts, bilateral symmetry, direct development, sensory structures of single-felled ocelli and statocyst
Have cuticle that can be shed, the blastopore turns into mouth, first group of protostomes