unit 2 learning objectives

DNA, Genes, and Biotechnology

  1. Describe the structure and classification of nucleotides and their role in nucleic acid formation.

DNA- deoxyribose sugar (1 oxygen), phosphate group, nitrogenous base (adenine, guanine, cytosine, thymine), double helix, double stranded

RNA- ribose sugar (2 oxygen), phosphate group, nitrogenous base (adenine, guanine, cytosine, uracil), single stranded

hydrogen bonds between base pairs, covalent between molecules in phosphodiester backbone

  1. Describe and interpret the molecular processes underlying the flow of genetic information, as defined by the Central Dogma of Molecular Biology (DNA → RNA → Protein).

DNA

Transcription

  • helicase unwinds DNA double helix

  • RNA polymerase starts at promoter region to decode one gene of DNA

  • uses uracil instead of thymine

  • result is pre-mRNA: RNA splicing by enzymes; cut out introns (stay in nucleus), leave extrons in (to exit nucleus to be decoded into proteins)

  • mRNA ready to leave the nucleus

RNA

Translation

  • now in cytoplasm or RER

  • initiation

    • tRNA anticodon binds to mRNA, binds to small ribosomal subunit, binds to large ribosomal subunit

  • elongation

    • A Site: amino-acyl site, tRNA anticodon binds to mRNA codon

    • P Site: peptidyl site, holds the growing polypeptide chain

    • E Site: where tRNA exits

    • when a protein binds or releases a ligand, the shape changes so that is how the ribosome moves along the mRNA

    • polysome: when multiple ribosomes working on the same mRNA

    • GTP needed for building proteins because it provides the energy for the peptide bonds between amino acids to form

  • termination

    • when mRNA stop codon

    • there is no complementary tRNA anticodon

    • so releases and polypeptide strand either stays in cytoplasm or goes to ER to be modified then sent out of the cell

Protein

  1. Identify the key enzymes and molecular components involved in transcription and translation, and explain their functions.

Transcription:

  • helicase- unwinds DNA double helix

  • RNA polymerase- makes RNA polymers (mRNA)

  • spliceosome- in charge of RNA splicing

Translation:

  • small ribosomal subunit: makes the polypeptide chain

  • large ribosomal subunit: holds the polypeptide chain, acts as enzyme for it being made

  • GTP- provides energy for peptide bonds to be made

  1. Apply knowledge of the Central Dogma to accurately transcribe and translate a given DNA sequence by hand.

GAC TTG CCG AAT CAG

  • transcribe into RNA: CUG AAC GGC UUA GUC

  • translate into amino acids: Leu Asn Gly Leu Val

  1. Differentiate and characterize the four primary types of genetic mutations and their potential effects on gene expression.

Frameshift: deletions and insertions, may cause wrong amino acids bc entire frame shifts

Silent: base pair substitution but codes for the same amino acid, no effects

Missense: base pair substitution that codes for a different amino acid, may be a big deal or not a big deal, just depends

Nonsense: base pair substitution that codes for a stop codon, gonna make the polypeptide chain too short so not functional

Cell Reproduction and Cancer

  1. Describe the stages of the cell cycle and explain the major events that occur during each phase.

  • Interphase

    • cell’s normal function

    • G1: cell is growing

    • S: DNA replication

    • G2: preparing for cell division

  • Prophase

    • nuclear membrane breaks down

    • chromosomes condense

    • prometaphase: spindle fibers penetrate nuclear membrane, attach to chromosomes

  • Metaphase

    • chromosomes line up at metaphyseal plate

  • Anaphase

    • sister chromatids pulled apart by spindle fibers

    • spindles pushing to stretch cell membrane and separate

  • Telophase

    • chromosomes at opposite poles, start to unwind

    • nuclear membranes form

    • cleavage furrow

    • microtubules also pulling cell membrane in

  • Cytokinesis

    • cells completely separated

  1. Compare and contrast mitosis and meiosis in terms of purpose, processes, outcomes, and biological significance.

    • Identify the types of cells that undergo mitosis and meiosis, and explain the significance of each process in growth, repair, and reproduction.

    • Recognize and describe key intracellular events (e.g., chromatin condensation, spindle formation, crossing over), specify when and where they occur, and explain their biological consequences.

Mitosis

  • to replace and repair tissues

  • somatic cells

  • makes diploid cells

  • all identical

  • 1 DNA replication for 1 division

Meiosis

  • to reproduce

  • germ cells/ gametes

  • makes haploid cells

  • all genetically different

  • 1 DNA replication for 2 divisions

  • crossing over in prophase I, independent assortment in anaphase I and II

  • chromosomes do NOT unwind in telophase I because they go right into prophase II

  1. Differentiate spermatogenesis and oogenesis in terms of timing, location, number of gametes produced, and cellular differentiation.

    • Explain the mechanisms and consequences of X chromosome inactivation and the role of the SRY gene in sex determination.

Spermatogenesis

  • starts at puberty, in seminiferous tubules (from periphery to lumen), finishes meiosis II in epididymis

  • spermatogonia (stem cells) go through mitosis to make one daughter stem cell and one daughter spermatocyte

  • spermatocyte goes through meiosis to make 4 sperm

Oogenesis

  • starts as an embryo, stops in prophase I, begins again at puberty, stops at metaphase II, finishes meiosis at fertilization

  • in ovaries, cells at different stages throughout

  • 1 egg/ovum ovulated per month

  • meiosis makes one ovum and 3 polar bodies (become dumping ground for extra chromosomes)

X Chromosome Inactivation

  • one X chromosome IN FEMALES is turned off

  • covered in special RNA and becomes a Barr body

  • about half cells have paternal X turned off, about half cells have maternal X turned off

SRY gene

  • gene on Y chromosome

  • contains TDF gene (testis determining factor)

  • determines gender

  1. Describe the molecular basis for cancer and how it develops

  • tumor suppressor gene must be mutated

  • mutagenic environment

  • become immune to apoptosis

  1. Describe the 4 types of point mutations and their consequence

  • frameshift: insertion or deletion

  • silent: codes for same amino acid

  • missense: codes for a different amino acid

  • nonsense: codes for a stop codon

  1. Understand important terminology related to cancer (apoptosis, cell-cycle checkpoint, oncogene/protooncogene, tumor, tumor suppressor, angiogenesis, malignant, benign)

  • apoptosis: programmed cell death, cells shrink away

  • cell cycle checkpoints

    • G1: check DNA is intact and environment is good to divide

    • S and G2: check DNA replicated correctly

    • Metaphase: check microtubules attached correctly and chromosomes aligned

  • oncogene: mutated proto-oncogene, doesn’t cause cancer just increases risk

  • proto-oncogene: encourages cell division

  • tumor: bunch of cancerous cells packed together

  • tumor suppressor: stops cell cycle is there is an issue, initiates apoptosis

  • angiogenesis: tumor secretes angiogenin which encourages blood vessels to grow near it and supply the tumor with nutrients instead of supplying healthy cells

  • malignant: tumor spreads

  • benign: tumor doesn’t spread

Genetics and Biotechnology

  1. Know the common methods used in biomedical research

  • model research organisms: similar to human genes, cheap and fast experiments, shorter life spans

  • gene sequencing: DNA polymerase uses regular and modified nucleotides, when modified stops sequence, run through gel, shine light through to see which nucleotide, see order

  • gel electrophoresis: restriction enzymes in with DNA, SNPs so may cut may not, run through agarose gel, DNA runs to positive cathode away form negative anode, large chunk gets caught so can’t travel as far, compare to ladder to see base pair amounts

  • immunohistochemistry: assess and locate specific proteins

  • polymerase chain reaction: increases by exponential amplification

    • denaturation: 95 Celsius, strands come apart

    • annealing: 55 Celsius, primers attach

    • extensions: DNA polymerase attaches nucleotides to strands

  • fluorescence in situ hybridization: identify and locate specific DNA sequences

  1. Understand and be able to apply important terminology ( e.g. model organism, aneuploidy, homologous structures, analogous structures, divergent vs convergent evolution, etc. ) .

  • model organisms: test subjects

  • aneuploidy: chromosome number not multiple of 23

    • trisomy (2n+1)

    • monosomy (2n-1)

  • homologous structures: divergent evolution, share same shape or function

  • analogous structures: convergent evolution, share same shape or function

  • divergent evolution: from same common ancestor

  • convergent evolution: developed same thing independently

  1. Understand and be able to apply important terminology from both Genetics chapters (e.g. linkage, carrier, karyotype, nondisjunction, pleiotropy, codominance, etc.).

  • linkage: genes close together very likely to be inherited together

  • carrier: heterozygous for a less than optimal gene

  • karyotype: pic of chromosomes, colchicine freezes in metaphase

  • nondisjunction: chromosomes don’t separate properly

  • pleiotropy: wide ranging effects of one gene

  • codominance: both alleles expressed fully

  • incomplete dominance: blended dominance, heterozygote somewhere in between two homozygotes

  • polygenic traits: affected by many genes like eye or hair color

  • multifactorial traits: affected by one or more genes and environment

  • sex influenced: genes are same in both genders but your sex determines how it’s shown

  • sex limited: only genes appropriate for your gender are expressed

  • sex linked: on X chromosome, like colorblindness

  1.  Be able to use a Punnett square to predict offspring genotypes and phenotypes (autosomal and sex linked)

yep I can do that

  1.  Identify instances of  Non-Mendelian inheritance in humans

  • codominance

  • pleiotropy

  • polygenic traits

  • incomplete dominance

  • linkage