EXAM 2 - Unit 4,5,6 Genomes and Evolution

Genomes and Evolution University of San Diego

Prokaryotes

Simplest, unicellular, characterized by a lack of mebrane-bound nucleus, DNA is singular located in nucleoid, plants and bacteria

Eukaryotes

Larger, more complex cells defined by a membrane nucleus where genetic material is stored, have membrane bound organelles that divide the cell into compartments for specific functions, multicellular, animals

Autotrophs

Organisms that can synthesize their own food from inorganic carbon (CO2​).

Heterotrophs

Organisms that obtain carbon by consuming organic compounds from other organisms.

Phototrophs

Organisms that use light (photons) as their primary energy source.

Chemotrophs

Organisms that obtain energy by oxidizing chemical compounds.

Photoautotrophs

Use light for energy and CO2​ for carbon (e.g., Plants).

Chemoautotrophs

Use Inorganic Chemicals for energy and CO2​ for carbon (e.g., Deep-sea vent bacteria).

Photoheterotrophs

Use Light for energy but require Organic Compounds for carbon (Rare bacteria).

Chemoheterotrophs

Use Organic Compounds for both energy and carbon (e.g., All Animals, Fungi).

Obligate aerobes

Use o2 for cellular respiration

Facultative anaerobes

Use o2 if it is present by carrying out anaerobic respiration or fermentation in anaerobic environment

Obligate anaerobes

Poisoned by o2 so they use anaerobic respiration or fermentation

Endosymbiont theory

eukaryotic organelles originated from free-living prokaryotic cells (bacteria) that were engulfed by larger host cells that led to their integration as semi-autonomous organelles within complex eukaryotic cells

Mitosis

The process of cell division used for growth, repair, and asexual reproduction, occurring in the body's somatic cells. Consists of only one division and results in two genetically identical daughter cells that maintain the diploid (2n) chromosome number of the parent cell.

Meiosis

The process of cell division used exclusively for the production of gametes (sex cells), occurring only in the specialized germ cells of the reproductive organs. Involves two sequential divisions (Meiosis I and Meiosis II) and results in four genetically unique daughter cells, each containing the haploid (n) number of chromosomes. The unique genetic variation in Meiosis is achieved primarily through the process of crossing over, which occurs during Prophase I.

Gene expression

The instructions in DNA are used to create functional products, primarily proteins or functional RNA, which carry out most of a cell's work, controlling when, where, and how much of these products are made, allowing cells to adapt and function.

Gene regulation

Regulation ensures that the right genes are "turned on" or "turned off" at the right time and in the right amounts, allowing cells to differentiate and respond to the environment.

Prokaryotes regulation

genes are often organized into operons, where several related genes share one switch, allowing the cell to turn them all on or off together easily. Since prokaryotes lack a nucleus, they can start translation immediately after transcription, making this control system very fast and efficient for reacting to changes in their environment.

Eukaryotes regulation

Control starts before transcription by adjusting the chromatin structure, making the DNA either accessible or tightly packed away. If a gene is transcribed, it is heavily regulated afterward through alternative splicing, which lets one gene produce several different proteins, and by using microRNAs to destroy or silence the mRNA.

Anabolic pathways

Need repressor to stop the production because they are constantly on

Catabolic pathways

Need activator to remove repressor and start production

Cleavage

The process of cell division that occurs in a rapidly dividing zygote (fertilized egg) immediately after fertilization.

Ways of Gene regulation in eukaryotes

chromatin packing, using same control elements (enhancer and activators) , areas that are rich in transcription factors

Hox genes

regulatory genes that act as master control switches for differentiation and development in almost all animals.

Asexual reproduction

Offspring that is identical to parent

Sexual reproduction

Combining genes from both parents that produce a genetically unique individual

Two fold cost of sex

Only fifty percent of genetic material is passed and females have to make twice as many offspring because males cant independently reproduce

Origins of genetic variation among offspring

Independent assortment, crossing over, and random fertilization

Reproduction of plants

Plant sexual reproduction is special because it involves two phases: a tiny haploid stage and a larger diploid stage (called alternation of generations). Haploid sex cells (gametes) fuse to make a diploid cell, which then grows into the plant we see. This process ultimately leads to the creation of seeds (which contain multicellular embryos) and spores (which are unicellular).

Reproduction of animals

two special haploid cells (sperm and egg) combine to make one new diploid cell (the zygote). This new cell then grows through many divisions to become a new multicellular animal.

Reproduction of fungi

First, the cells from two different parents merge their insides (cytoplasm fusion). Next, their nuclei finally merge (nuclear fusion) to create a new diploid nucleus. This diploid cell then immediately divides to make new, genetically mixed unicellular spores that grow into a new fungus.