Unit 2: Biological basis of life, heredity, and genetics

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Issues with Darwin's Evolutionary Theory

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Cells - General CompositionOrganelles - substructures in the cell which do different things involved in the function of the cell, e.g. protein synthesis, nutrient conversion, energy storage and release, waste disposal, etc.

Important OrganellesNucleus - houses both DNA and RNA molecules

Ribosomes - organelles in part made up of RNA; involved in protein synthesis

Mitochondria - powerhouse of the cell - produces energy; think: cell's engines; also has DNA: mtDNA

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Cells - Two typesSomatic cells - body tissues eg organs, brain, bone, and muscle

Sex cells (gametes) - unites with another gamete from another individual which forms a zygote. They transmit genetic information from parents to offspring.

Zygote - Potential to develop into a new organism, contains all the chromosomes (46 for us)

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ProteinsFunction - attach to various molecules to perform different functions

Hemoglobin (Hb) - binds w/ oxygen and transports it around the body

Collagen - (tissue composition) - most common protein in the body

Enzymes - regulate chemical reactions; E.g., digestive enzyme lactase breaks down lactose into simpler sugars.

Hormones - affect different tissues and organs. Insulin is made by specialized cells in the pancreas causes liver cells to absorb glucose from blood

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DNADNA (deoxyribonucleic acid) - Double-stranded host of the genetic code

RNA (ribonucleic acid) - single-stranded molecule

Three different compositions:messenger (mRNA)transfer (tRNA)

DNA + RNA houses genetic information responsible controlling the cell's functions

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DNA StructureNucleotides - 1. a sugar (deoxyribose), 2. a phosphate group,and 2.1 of 4 nitrogenous bases:

Bases - adenine (A), thymine (T), guanine (G), and cytosine (C)Bonds: AT and GC

Double helix Nucleotides: sugars and phosphates = ladder sides; bonded bases = rungs

Codon = Triplet - 3 bases specify a given amino acid (e.g., CGA specifies arginine)

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Protein Synthesis, an activity performed by DNAStarts with messenger RNA takes the copied DNA message out of the nucleus

RNA - single-stranded and contains a different sugar and base uracil (U) instead of thymine. -Adenine usually binds with thymine but it also binds with uracil

mRNA is generated and peels away from DNA to leave the nucleus

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Protein SynthesisDNA directs the assembly of proteins in cells

Proteins structure - chains of amino acids

Amino acids - 20 different amino acids

12 produced by cells but 8 are obtained by diet in humans.

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Protein Synthesis, an activity performed by DNAmRNA is decoded in ribosomes - mRNA have triplets or codons code for specific amino acids

tRNA goes to ribosomes where amino acids join wrt mRNA codons potentially makes a protein or protein part.

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Genes - structures and functions"a sequence of DNA bases that specifies the order of amino acids in an entire protein, a portion of a protein, or any functional product [like RNA]" (58p)

Structure

Composition: 100s-1000s of nucleotide basesOrganization: coding and noncoding segments

FunctionRegulatory genes - to switch on/off other DNA segments.E.g., Hox genes - direct body plan development and embryonic tissue segmentation. 11

ChromosomesStructure - Coiled DNA + proteins

Locus - location of a gene on a chromosome.

Types

Autosomes - also paired and abnormal numbers of sex chromosomes can cause sterility or non-fatal consequences.

Sex chromosomes = X and Y - X chromosome functions like autosomes; Y chromosome denotes an organism's sex in mammals.

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ChromosomesHumans have 46 chromosomes, whereas gorillas and chimpanzees have 48.

Karyotype - Chromosomes are visible during cell division

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DNA replication-before cell division in the nucleus

-Replication starts when a DNA molecule unzips exposing the bases

-free-floating nucleotides pair with complementary bases

--formulation of two new DNA molecules which packaged up to form the sets of chromosomes allotted to each daughter cell

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DNA replication - Making copies of itselfEnzymes - catalysts - breaks DNA base bonds which are able to connect to other DNA bases on DNA in the nucleus.

Bonds: AT and GC - connects to another DNA strand to form two new DNA molecules

A Train Goes Choo-choo

Apples on Trees and Cars in Garage

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Cell Division - Mitosis and meiosisMitosis - creation of two cells from one-Somatic cells (muscles, brain, blood cells, etc)

Phase 1: DNA replication - 46 single-stranded chromosomes become 46 double-stranded chromosomes.

Phase 2: Cell division - 46 double-stranded chromosomes are split and make up the genetic material in two daughter cells.-Daughter cells are identical - 46 single-stranded

Result: daughter cells each with 46 chromosomes and identical to the parent cell-DNA returns to directing protein manufacturing

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Cell Division - Meiosis Gametes-Two divisions - a reductive one a second cell division.

Reductive division - similar to the process in mitosis; results in two cells each containing 23 double-stranded chromosomes.

Second division - 23 double-stranded chromosomes align and pulled apart at the centromere also similar to mitosis; results with four daughter cells all possessing the haploid number of chromosomes.

Haploid number = n = number of chromosomes in the gametes. For humans it is n = 23.

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Anthropology connectionsThe Human Genome Project was made possible. -sequenced all 30,000 genes humans have in their genome.

The Neandertal Genome has also been sequenced and same with the Chimpanzee genome...600 other species as well. -compare and contrast the characteristics found among the genomes in order to better understand our own evolutionary history.

Stem cells - Undifferentiated cells > able to divide and differentiate into other cell types (e.g., a cell that could become a blood, liver, or kidney cell)

Need more background but here’s a non-terrible video.https://youtu.be/evH0I7Coc54 18