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111 Cards in this Set
- Front
- Back
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What do chromosomes contain?
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Genetic material
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DNA (genes) are located where?
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on chromosomes
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DNA (genes) do what?
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control features
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When do chromosome pairs seperate?
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during meiosis
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Definition: Character
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feature of organism; may vary (i.e. eye color, height)
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Definition: Gene
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individual unit of genetic information for specific characters (on specific locations on chromosomes)
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Definition: Alleles
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alternative versions of gene; why we are not all identical although we may have same genes
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How do allels arise?
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change in DNA/mutation; those in gametes are inherited
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How many alleles can an individual have?
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2 but there can be any number in species
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Definition: homozygous
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have two copies of same allele (AA or aa)
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Definition: heterozygous
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have two different alleles (Aa)
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Definition: phenotype
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organism's observable characteristics (eye color, skin color)
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Can a phenotype have different alleles?
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Yes
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Definition: genotype
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what genes and alleles are present
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Definition: dominant allele
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phenotype expressed in heterozygote (Aa <-- the capital letter)
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Definition: Recessive allele
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phenotype that is not expressed in heterozyogot (Aa <-- lower case letter)
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Definition: genetic cross
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controlled mating to determine inheritance
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Definition: P generation, F1 generation, F2 generation
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parent of cross, first generation, second generation
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Definition: retain idenity
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characters can be recovered in F2; all genes are there but only one is dominate over the other
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Mendel's Laws
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1. units of inheritance behave in certain ways 2. a characters inheritance is predictable 3. the results can be measured
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Law of segregation
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2 alleles of a gene go into seperage gametes during meiosis. both alleles are passed on and are equally represened in gamates.
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Law of independent assortment
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how the 2 alleles of one gene go into gametes does not affect how the allels of other genes go into gametes. however if on same chromosome they tend to travel together
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Alleles can arise by a _ which occurs where?
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mutation; 1. present in parents (majority of the cases and so it is inherited) 2. occurred in making of gametes 3. appeared in new individual
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How do we determine how a trait is inherited
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a pedigree analysis - which analyzes existing mating
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Pedigree analysis
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best for simple traits that are controlled by one gene (complete dominance) and not affected by the environment
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Definition: autosomal
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non-sexed chromosomes
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autosomal recessive traits
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expressed only if homozygous recessive; may hide in carriers and "skip" generations
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autosomal dominant traits
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expressed if homozygous dominant or heterozygous dominant; cannot hide
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X-linked traits for a male
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if expressed in male he has allele (it cant be hidden in a male b/c he only has one x) - SAME for recessive or dominant
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x-linked trait for a female
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if expressed: she is homozygous recessive; if not expressed she is homoygous dominant or homozygous (a carrier) - SAME for recessive or dominant
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x-linked recessive genes are more common in male or female?
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male b/c recessive gene can't be masked (males have only one X)
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x-linked dominat genes are more common in male or female?
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female
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DNA chemical componets
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sugar phosate base (nucleotide) + the bases
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Describe a DNA structure
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double helix, 3D, sugars and phosates form sides, bases pair (A + T, C + G )
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Linkage violates which principle?
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The principle of independent assortment
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The greater the distance b/w genes...
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...the higher exchanged frequency b/w them
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DNA combines with what to form a chromosome?
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a protien
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Definition: interphase
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cell grows and accumlates materials, new materials and organelles are made, DNA/chromoms duplicate
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Definition:Cell division
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when a single cell becomes two daugher cells (used for growth/replacement - make more cells - and reproduction - make new individuals -)
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Chromosomes at the start of interphase are
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single and invisible
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Chromosomes at the end of interphase
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are doubled and invisible
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When are chromosomes are visible?
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at the start of cell division
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Definition: amino acid
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a building block of a protein molecule
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Definition: anticodon
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the triplet of nucleotides in a tRNA molecule pairs with a specific triplet codon in mRNA during protein synthesis
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Definition: catalyst
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substance that increases the rate of a reaction w/o being used up in the reaction
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Definition: centomere
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a specialised part of a chromosome which attaches the chromatids togther during the early stages of cell division
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Definition: codominance
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two or more alleles making a positive contribution to a phenotype resulting in blending of characters
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Definition: codon
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atriplet of nucleotide bases in DNA that codes for a specific amino acid in protein synthesis
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Definition: continuous variation
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a type of variation which shows an even graduation b/w 2 extremes in a population
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Definition: crossing over
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a process of exchange b/w paired chromosomes which may give rise to new combinations of characters. it takes place by the breaking and rejoiing of chromatids and leads to the formation of chiasmata.
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Definition: dihybrid
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a hybrid heterozygous at two loci and obtained by crossing homozygous parents with different allels at two give loci (i.e. YYRR + yyrr = YyRr)
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Definition: discontinuous variation
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a variation in populations where the indiviuals fall within two or more distinct groups with respect to a particular character.
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Definition: enzyme
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a protien which alters the rate of chemical reactions
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Definition: eugenics
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theory that the human race could be improved by contolled selective breedingb/w individuals with 'desirable' traits
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Definition: genetic code
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the means by which ino is carried in the genetic material to control protein synthesis
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Definition: genome
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the total genes in a basic set of chromosome of an organism
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Definition: genotype
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the genetic make-up of an organism with regard to a given pair of alleles i.e. a tall pea plant's genotype could be TT or Tt
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Definition: haploid
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only one set of chromoes (i.e. gametes)
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Definition: hybrid
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any offspring produced by sexual reproduction b/w 2 visibly different parents
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Definition: ligase
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an enzyme which cloese breaks in single-stranded DNA (combines them)
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Definition: meiosis
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cell division in which the chromost # is halved so that the diploid cell gives rise to haploid cells (gametes)
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Definition: mRNA
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a single-stranded RNA molecule formed by transcription from DNA which carries the info encoded in the gene to the site of protein synthesis on the ribosome
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Definition: mitosis
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cell division in which daugther cells have the same number of chromosomes as the parent cell
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Definition: nucleotide
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the basic unity of nucliec acid molecules composed of a phospahte, a sugar, and a base
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Definition: phenotype
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the outward expression of a gene - the visible chracteristics shown by an organism
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Definition: polymerase
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an enzyme which catalyses the assembly of nucleotides into RNA or DNA on a DNA template during transcription
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Definition: restriction enzyme
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an enzyme that makes cuts in double-stranded DNA at specific sites
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Definition: ribosome
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a strcutre in a cell composed of RNA and proteins, where mRNA is translated and proteins synthesised
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Definition: transcription
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the process in which messenger RNA is syntheised from a DNA template
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Definition: translation
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the process by which the information carried in the base sequence of mRNA is used to produce a sequence of amino acis in protein synthesis
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Definition: replication
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the synthesis of DNA
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DNA replication steps
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1. two strands unwind and seperate, 2. each strance serves a template for other (new nucleotides base-pair connect, 3. result: 2 identicle double helices (each one part "old" and part "new"
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What is the role of enzymes in DNA replication?
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they help unwine, separate, start, attach, and connect
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Two ways DNA changes
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1. errors in copying (permanent in DNA sequence - forms new alleles) 2. damage from radiation + chemicals
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What are the roles of proteins in a cell?
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they determine phenotype and the structure, movement and protection in the cell
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Genes vs Proteins (roles)
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Genes control genotype, proteins control phenotype
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Genes vs Proteins (informational molecules)
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genes: DNA (storage and inheritance) ; proteins: amino acis (activity in cell)
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Genes and Proteins
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both use order of "letters" for information and languages which need RNA to convert
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RNA vs DNA
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difference sugar (ribose), single stranced, no thymine but uracil, smaler more moblie and short lived
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Transcription occurs where? and does what?
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DNA to mRNA --> "rewriting" the information, same language; occurs in nucleus
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Translation occurs where? and does what?
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mRNA to proteins --> "converting" to a different language; occurs in cytoplasm
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Transcription produces
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all 3 RNA types and a single stranded RNA
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which RNA carries infor for protiens
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only mRNA
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Each amino acid is coded for by...
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at least one codone
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true or false: a change in a codon will always change the amino acid
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false some codons are used for the same amino acid
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Translation steps
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1. initation 2. elongation 3. termination
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True or false: a change in one amino acid can affect protein funtion
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true - a small change can have large effects (i.e. sickle cell anemia)
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What is needed for genes to create phenotypes
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RNAs, proteins (enzymes), and the environment
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Bacteria transfer is hard or easy? why?
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DNA can trasfer easily b/w individuals b/c it is made up of simple cells
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How can bacteria spread?
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it can be picked up from environment, carried by viruses that infect bacteria, or transfrred through connections with other bacteria
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What is the consequence of a simple cell bacteria
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the resitance to drugs
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To take over host cell what much a virus be able to do?
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it must be able to replicate genetic material and control protein synthesis
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DNA viruses can use host cell's enzymes to...
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replicate and be trascribed into mRNA (which will then be translated)
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RNA viruses can be translated directly by using enzymes from..
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the virus; host cells don't have the enzyme for this
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Retroviruses (RNA viruses) are more dangerous b/c
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virus provides reverse transcriptase that has no proof-reading ability and high mutation rate
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when are chromatids seperated from each other?
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mitosis and meisos II
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homologous chromosome pair segreate into different daughter cells during
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meiosis I -------- key word: DIFFERENT
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2 types of nitrogen bases
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1. purine (adenine and guanine) 2. pyrimidine (cytosine and thymine and uracil)
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basic structure of DNA
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a phosphate, a 5-carbon sugar called deoxyribose, and one of four nitrogenous bases, adenine, guanine, cytosine and thymine
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When does DNA replicate?
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during interphase
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what happened when Mendel performed his crosses with plants that were not true-breeding?
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when a pruple flowered plant was crossed with a white flowered plant 100% of the plants produced purple flowers
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what happened when Mendel let the non true-breeding plants self pollate (F2)
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75% of the plants were purple 25% were white
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2 types of nitrogen bases
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1. purine (adenine and guanine) 2. pyrimidine (cytosine and thymine and uracil)
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basic structure of DNA
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a phosphate, a 5-carbon sugar called deoxyribose, and one of four nitrogenous bases, adenine, guanine, cytosine and thymine
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When does DNA replicate?
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during interphase
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what happened when Mendel performed his crosses with plants that were not true-breeding?
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when a pruple flowered plant was crossed with a white flowered plant 100% of the plants produced purple flowers
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what happened when Mendel let the non true-breeding plants self pollate (F2)
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75% of the plants were purple 25% were white
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a sequence of DNA that contains information for the synthesis of RNA molecules used in the manufacture of proteins is known as
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a gene
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the process of gene transcription begins with the
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bnding of RNA polymerase to a region of DNA called the promoter
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a small segment of DNA contains the base sequence CGT. If an mRNA transcript is made that includes this DNA sequence, what will be the anticodon on the tRNA that will bind to the corresponding mRNA codon for this DNA triplet?
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CGU
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To create a protein, which of the following sequences of events must take place?
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Transcription of DNA, translation of mRNA, protein formation
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