Chapter 3: Genetics and Genomics: Reproducing Life and Producing Variation Flashcards
What is genetic code?
DNA packaged in chromosomes
Nuclear DNA provides most genetic code
What does genetic code (DNA) do?
- Serves as the chemical template for its own replication and the creation of proteins
- First step in cell reproduction
What is the genetic basis for human variation?
- Genes are linear sequences of nucleotides that code for specific body structures and functions
- Each gene has a locus on each chromosome
- Each pair of chromosomes has a paternal and a maternal chromosome
- Genotypes are pased on two alleles and are expressed physically as phenotypes
- Most physical characteristics rely on multiple genes
Amino acids
Organic molecules combined in a specific sequence by the ribosomes to form a protein
Autosomes
All non-sex chromosomes that occur in pairs in all somatic cells
Codons
The sequences of 3 nitrogen bases carried by mRNA that are coded to produce specific amino acids in protein synthesis
Crossing-over
Process by which homologous chromosomes partially wrap around each other and exchange genetic info during meiosis
Diploid
Cell with a full complement of paired chromosomes
Epigenetic
Refers to chemical changes in the genome affecting how the underlying DNA is used in production of proteins, but without altering the DNA sequences
Gametes
Sexual reproductive cells, contain haploid number of chromosomes
Pair with other gametes during reproduction to form new organism
Genome
Complete set of genetic information for an organism or species that represents all inheritable traits
Haploid
Cell that has a single set of unpaired chromosomes
Haplogroups
Large set of haplotypes that may be used to define a population
Heterozygous
Condition in which the two alleles of a pair are different
AB for example
Homeotic (Hox) genes
Responsible for differentiating the specific segments of the body, such as the head, tail, and limbs, during embryological development
Homologous
Refers to each set of paired chromosomes in the genome
Homoplasmic
Refers to nuclear DNA, which is identical to the nucleus of each cell type
Homozygous
Condition in which the two alleles of a pair are the same
AA or aa for example
Karyotype
Characteristics of the chromosomes for an individual organism or a species such as number, size, and type
Typically presented as a photograph of someone’s chromosomes that have been arranged in homologous pairs and put in numeric order by size
Law of independent assortment
Mendel’s second law, which asserts that the inheritance of one trait does not affect the inheritance of other traits
Law of segregation
Mendel’s first law, which asserts that the two alleles for any given gene (or trait ) are inherited, one from each parent; during gamete production, only one of the two alleles will be present in each ovum or sperm.
Locus
Location on a chromosome of a specific gene
Meiosis
Production of gametes through one DNA replication and two cell (and nuclear) divisions, creating four haploid gametic cells
Microsatellites
Short tandem repeats STRs
Sequences of repeated base pairs of DNA, usually no more than 2-6
If repeated excessively, they are often associated with neurologic disorders like Huntington’s chorea
Mitochondria
Organells with their own DNA that produce energy ATP
Mitosis
Process of cellular and nuclear division that creates two identical diploid daughter cells
Nondisjunctions
Failure of the chromosomes to properly segregate during meiosis, creating some gametes with abnormal numbers of chromosomes
Nucleotide
Building block of DNA and RNA, composed of sugar, phosphate group, and one of four nitrogen bases (A, T, G, C)
Pleiotropy
A single gene can have multiple effects
Polygenic
One phenotypic trait is affected by 2+ genes
Polymorphism
Refers to the presence of two or more alleles at a locus and where the frequency of the alleles is greater than 1% in the population
Recombination
Exchange of genetic material between homologous chromosomes due to a crossover event
Regulatory genes
Determine when structural genes and other regulatory genes are turned on/off for protein synthesis
Replication
Process of copying nuclear DNA prior to cell division so that each new daughter cell receives a complete complement of DNA
Ribonucleic acid RNA
Single-strand molecule involved in protein synthesis, consissts of phosphate, ribose sugar, and one of four N bases
Ribosomes
Organelles attached to the surface of the endoplasmic reticulum, located in the cytoplasm of a cell
Site of protein synthesis
Sex chromosomes
Pair of chromosomes that determine biological sex
XX or XY
Single nucleotide polymorphisms SNPs
Variations in the DNA sequence due to the change of a single N base
Somatic cells
Diploid cells that form organs, tissues, and other body parts
Structural genes
Genes coded to produce particular enzymes, hormones, etc.
Transcription
1st step of protein synthesis, involves creation of mRNA based on the DNA template
Translation
2nd step of protein synthesis, involves transfer of amino acids by tRNA to the ribosomes, which are then added to the protein chain
Translocations
Rearrangements of chromosomes due to the insertion of genetic material from one chromosome to another
Zygote
The cell that results from egg fertilization
