Units 3 & 4 Flashcards
Scientists & Vocabulary
Gregor Mendel
crossing pea plants, pure breeding to examine differences. Discovered dominant and recessive traits, disproved blended inheritance. Principles of segregation and independent assortment
Thomas H. Morgan
observed crossover during meiosis concluded that “genes” are on chromosomes. He proposed the “beads on a string “ model. (explains how traits are passed on to the next generation)
Kary Mullis
Polymerase Chain Reaction (PCR), 1993 Nobel Prize
Hershey & Chase
DNA is the hereditary material, 1969 Nobel Prize
Oswald Avery
DNA is the transforming principle
Francis Crick
- recognized that although the DNA molecule had only four “letters,” it must code for the 20 amino acids that made up proteins. Concluded that the code for an amino acid must contain three bases, or triplets (codons)
- The Central Dogma
James Watson
DNA structure (double helix), 1962 Nobel Prize (along with Francis Crick)
Frederick Sanger
Human mitochondrion sequenced
True-breeding
a term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate
Dominant
An allele that is always expressed
Meiosis
Cell division that produces reproductive cells in sexually reproducing organisms
Gamete
Sex cell
Dihybrid cross
A cross between two individuals, concentrating on two definable traits
Chromosome
A threadlike, gene-carrying structure is found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins
Somatic cell
any cell of a living organism other than the reproductive cells (body cells)
Replication
Copying process by which a cell duplicates its DNA
The cell cycle
The regular sequence of growth and division that cells undergo
Genome
all of an organism’s genetic material
Codon
A specific sequence of three bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid
rRNA
ribosomal RNA; type of RNA that makes up part of the ribosome
Sister chromatid
a structure that contains identical DNA copies and is formed during DNA replication
Mutation
change in a DNA sequence that affects genetic information
Recessive
An allele that is masked when a dominant allele is present
Allele
Different forms of a gene
Zygote
fertilized egg
Regulatory gene
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes
Synapsis
the pairing of homologous chromosomes during meiosis
Eukaryote
A cell that contains a nucleus and membrane-bound organelles
Gene
A segment of DNA on a chromosome that codes for a specific trait
Sex cell
An egg or sperm cell (gamete); a sex cell carries half the number of chromosomes found in other body cells
Diploid
two complete sets of chromosomes, one from each parent
Central Dogma
a theory that states that, in cells, information only flows from DNA to RNA (transcription) to proteins (translation)
Ribosome
Cytoplasmic organelles at which proteins are synthesized
Chromatin
A substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones
Mendelian trait
a trait completely determined by a single gene
F1 generation
the first generation of offspring obtained from an experimental cross of two organisms
Genotype
the genetic makeup of an organism
Homozygous
Having two identical alleles for a particular gene/trait
Mitosis
cell division in which the nucleus divides into nuclei containing the same number of chromosomes
Translation
The process by which mRNA is decoded and a protein is produced
Autosome
Any chromosome that is not a sex chromosome
Reduction division
another name for meiosis I, the division where homologous pairs separate
Sex chromosome
one of two chromosomes that determines an individual’s sex
Haploid
An organism or cell having only one complete set of chromosomes
mRNA
messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
Amino acid
Building blocks of protein
DNA base
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Blending inheritance
n outdated, incorrect theory that the phenotype of an offspring is a blend of the parent’s phenotypes
F2 generation
Offspring resulting from the interbreeding of the hybrid F1 generation
Phenotype
An organism’s physical appearance, or visible traits
Heterozygous
An organism that has two different alleles for a trait
Universal genetic code
refers to the fact that particular codons specify the same amino acids in almost all organisms
Transcription
the process whereby the DNA sequence in a gene is copied into mRNA
Complementary base pairing
- In DNA, T pairs with A and G pairs with C;
- In RNA, U pairs with A and G pairs with C
Crossing over/Recombination
when homologous chromosomes trade parts of chromosome arms
Homologous
the term used to refer to chromosomes that each has a corresponding chromosome from the opposite-sex parent
Tetrad
structure containing 4 chromatids that form during meiosis
tRNA
transfer RNA; type of RNA that carries amino acids to the ribosome
Cytoplasm
A jellylike fluid inside the cell in which the organelles are housed
Homologous chromosomes
Chromosomes that have the same sequence of genes and the same structure