Unit 3

Unit 3

CH 11: Sexual Reproduction and Meiosis
1. SEXUAL LIFE CYCLES
  1. HAPLOID
    1. HAPLOID CELLS
      1. 1 copy of each chromosome
      2. GAMETES
  2. DIPLOID
    1. DIPLOID CELLS
      1. 2 copies of each chromosome
      2. GERMLINE CELLS
        undergo meiosis and reduce chromosome from 2n to 1n into gametes
      3. ZYGOTE
        undergoes mitosis to continue to produce diploid cell
        to become a viable organism/offspring; needs to get bigger thru mitosis (growth)
    2. in most animals diploid dominates
2. SEXUAL REPRODUCTION
  1. meiosis and fertilization constitute a cycle of reproduction
  2. inherit 23 chromosomes from both parents
    1. MOTHER
      1. MATERNAL HOMOLOGUE
      2. EGG
      3. XX
    2. FATHER
      1. PATERNAL HOMOLOGUE
      2. SPERM
      3. XY
        male sperm determines gender of offspring
  3. sperm and egg fuse for fertilization to take place resulting in a zygote
    1. FERTILIZATION restores diploid # (1n plus 1n equals 2n)
3. MEIOSIS
  1. 2 ROUNDS OF DIVISION
    1. MEIOSIS I
      1. PROPHASE I
        chromosomes condense, nuclear envelope disappears, spindle apparatus forms, synapsis, crossing over
        SYNAPIS
        homologous chromosomes become closely associated
        CROSSING OVER
        genetic material exchange
        allows for genetic variety
      2. METAPHASE I
        chiasmata hold homologues together, homologues align at metaphase plate, spindles attach to homologues
      3. ANAPHASE I
        chiasmata break, chromosomes pulled to opposite poles (each pole has complete haploid), separates homologues
      4. TELOPHASE I
        nuclear envelope reforms, sister chromatids not identical (diversity)
    2. MEIOSIS II
      1. PROPHASE II
        chromosomes
      2. METAPHASE II
      3. ANAPHASE II
      4. TELOPHASE II
        4 daughter cells (1 copy of each chromosome)
  2. ERRORS OF MEIOSIS
    1. ANEUPLOID GAMETES
      1. missing or extra chromosomes in gametes
    2. NONDISJUNCTION
      1. genetic disorder, too many or too less chromosomes
  3. MEIOSIS FUNCTION
    1. production of gametes
    2. mitosis function is growth and repair
  4. MEIOSIS FEATURES
    1. (compare mitosis and meiosis)
    2. synapsis + crossing over
    3. sister chromatids joined in meiosis I
    4. kinetochores of sister chromatids attach to same pole
    5. DNA replicating suppressed
    6. independent assortment
    7. 2n to 1n
  5. also referred to as REDUCTION DIVISION
    1. chromosome #s reduce, divides cell into four daughter cells
CH 12: Patterns of Inheritance
1. PRINCIPLE OF INDEPENDENT ASSORTMENT
  1. PRINCIPLE OF SEGREGATION
    1. 2 alleles for a gene segregate during gamete formation (meiosis)
      1. rejoined at random, one from each parent, during fertilization
  2. in dihybrid cross, alleles for each gene assort differently
    1. traits separate independently in gamete formation
2. EPIGENTICS
  1. EPISTASIS
    1. behaviour of gene products change ratio
  2. how genes react w/ other molecules
3. POLYGENIC INHERITANCE
  1. PLEIOTROPHY
    1. GENE
      1. ALLELE
        DIHYBRID CROSS
        MONOHYBRID CROSS
        *punnet square
        F1 GENERATION
        F2 GENERATION
        breed F1 offspring
        offspring in first cross
        two traits; four outcomes ---> 16 outcomes
        different forms of the same gene
      2. segment of DNA found on chromosome, codes for protein
  2. DOMINANT
    1. INCOMPLETE DOMINANCE
      1. CODOMINANCE
        heterozygote shows both traits (co means with)
        RECESSIVE
        masked by dominant allele
        HOMOZYGOUS RECESSIVE
        HOMOZYGOUS DOMINANT
        HETEROZYGOUS
        GENOTYPE
        PHENOTYPE
        physical characteristic
        genetic makeup
      2. blend, alleles do not mask eachother
    2. dominant allele masks recessive allele
CH 13: Chromosomes, Mapping, and the Meiosis-Inheritance Connection
1. SEX LINKAGES
  1. sex linked conditions reside on X or Y chromosome
  2. certain genetic disease affect males to a greater degree than females
2. X CHROMOSOME
  1. is larger than Y chromosome
  2. more sex linked conditions because it's bigger
  3. in FEMALES, one X chromosome is inactivated
  4. carries essential genes
3. GENETIC MOSAICS
4. Y CHROMOSOME
  1. smaller than X chromosome, not a lot of info
5. CHROMOSOME THEORY EXCEPTIONS
6. GENOMIC IMPRINTING
  1. "Which parent contributed the alleles?"
CH 14: DNA: The Genetic Material
1. DNA STRUCTURE
  1. DNA is a nucleic acid
    1. nucleic acid is made up of NUCLEOTIDES
      1. NUCLEOTIDES
        are made up of:
        DEOXYRIBOSE
        PHOSPHATE GROUP
        NITROGENOUS BASE
        PURINES
        Adenine and Guanine
        PYRIMIDINES
        Thymine and Cytosine
        Uracil (RNA)
        COMPLEMENTARY BASE PAIRING
        A to T
        AMOUNT OF A = AMOUNT OF T
        G to C
        AMOUNT OF G = AMOUNT OF C
        HYDROGEN BONDS joins nitrogenous bases
        "easy to make, easy to break"
      2. PHOSPHODIESTER BONDS
        joins two nucleotides
  2. DNA is a double stranded molecule
    1. "COOLING STRAND"
    2. "TEMPLATE STRAND"
      1. *template means pattern
      2. used to make mRNA
2. CELLS REPLICATE DNA TO REPRODUCE
  1. DNA is replicated during SYNTHESIS
3. DNA is made in 5 PRIME TO 3 PRIME direction
4. DNA POLYMERASE
  1. ENZYMES RESPONSIBLE FOR MAKING DNA
CH 15: Genes and How They Work
1. CENTRAL DOGMA OF BIOLOGY
  1. information flows in one direction
    1. DNA ---> RNA
    2. RNA ---> PROTEIN
  2. EXCEPTION:
    1. RETROVIRUSES use the enzyme, REVERSE TRANSCRIPTASE to convert RNA to DNA
2. PROTEIN SYNTHESIS
  1. TRANSCRIPTION
    1. RNA POLYMERASE
      1. used to make RNA
        NOT a good proofreader
  2. TRANSLATION
    1. tRNA, TRANSFER RNA, transfers amino acids to ribosomes
      1. RIBOSOMES: site of protein synthesis
        ribosomes are made of two subunits
      2. peptide bond forms between amino acids on protein
  3. IMPORTANT FOR PROTEIN SYNTHESIS:
    1. mRNA
    2. tRNA
    3. rRNA
3. DIFFERENCES IN RNA AND DNA
  1. RNA
    1. single stranded
      1. A-U
        ribose
  2. DNA
    1. double stranded
      1. A-T
        deoxyribose
4. CODONS
  1. STOP CODONS
    1. terminates translation; stops process
      1. UUA, UGA, UAG
  2. START CODONS
    1. start of translation
      1. AUG
  3. a codon is 3 NUCLEOTIDES in a row
    1. code is degenerate; multiple codons code for the same amino acid
  4. "WOBBLE EFFECT"
    1. mutation of the third nucleotide does not affect amino acid
5. MUTATIONS
  1. POINT MUTATION
    1. alters a single base, can be SPONTANEOUS or INDUCED
      1. SPONTANEOUS MUTATIONS
        cause: DNA polymerase proofreads incorrectly
      2. INDUCED MUTATIONS
        cause: radiation, chemicals
  2. FRAMESHIFT MUTATION
    1. more profound effects than point mutation
      1. changes reading frame
        the addition or deletion of a base
    2. TRIPLET REPEAT EXPANSION MUTATION
  3. CHROMOSOMAL MUTATIONS
    1. changes structure
      1. DELETION
        genes deleted from chromosome, chromosome lacks gene
        DUPLICATION
        INVERSION
        genes become inverted (flip-flopped)
        RECIPROCAL TRANSLOCATION
        moving genes from one place to another
        genes duplicated, multiple copies of genes on chromosome
EUKARYOTES
1. DNA in EUKARYOTES is LINEAR
2. PLANTS, ANIMALS, FUNGI, AND PROTISTS
PROKARYOTES
1. DNA in PROKARYOTES is CIRCULAR
2. BACTERIA and ARCHEA
SICKLE CELL DISEASE
1. single point mutation of one base
  1. causes red blood cell to take on a sickle shape
    1. spleen filters out sickle shaped red blood cells
      1. person does not have enough red blood cells to carry oxygen to cells
        person gets anemia, anemic people are tired

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