BioAnth chap 2
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48 terms
Terms | Definitions |
|---|---|
 prokaryotes | single-celled organisms, such as bacteria, in which the genetic material is not separated from the rest of the cell by a nucleus |
| eukaryotes | a cell that possesses a well-organized nucleus |
| nucleus | in eukaryotic cells, the part of the cell in which the genetic material is separated from the rest of the cell (cytoplasm) by a plasma membrane |
| cytoplasm | the region within the cell membrane that surrounds the nucleus; it contains organelles, which carry out the essential functions of th cell, such as energy production, metabolism, and protein synthesis |
| somatic cells | the cells of the body that are not sex cells |
| gametes | sex cells; sperm in males or eggs/ ova in females |
| stem cells | undifferentiated cells found in the developing embryo that can be induced to differentiate into a wide variety of cell types or tissues... also found in adults, although adult stem cells are not as totipotent as embryonic stem cells |
| DNA | deoxyribonucleic acid... a double-stranded molecule that is the carrier of genetic info, each strand composed of a linear sequence of nucleotides; the two strands are held together by hydrogen bonds that form between complementary bases |
| proteins | complex molecules formed from chains of amino acids (polypeptide) or from a complex of polypeptides; function as structural molecules, transport molecules, antibodies, enzymes and hormones |
| protein synthesis | assembly of proteins from amino acids, which occurs at ribosomes in the cytoplasm and is based on info carried by mRNA |
| RNA | single-stranded nucleic acid that performs critical functions during protein synthesis and comes in three forms, messenger, transfer, and ribosomal |
| mitochondria | organelles in the cytoplasm where energy production for the cell takes place... contains its own DNA |
| endoplasmic reticulum (ER) | an organelle in the cytoplasm consisting of a folded membrane |
| ribosomes | structures composed primarily of RNA, which are found on the ER and are the site of protein synthesis |
| nucleotide | molecular building block of nucleic acids DNA and RNA; consists of a phosphate, a sugar, and a base |
| base | variable component of the nucleotides that form the nucleis acids DNA and RNA, in DNA the bases are adenine, guanine, cytosine, and thymine... in RNA, uracil replaces thymine |
| enzyme | a complex protein that is a catalyst for chemical processes in the body |
| hemoglobin | proteins found in red blood cells that transport oxygen |
| hormone | a natural substance produced by specialized cells in one location of the body that influences the activity or physiology of cells in a different location |
| amino acids | molecules that form the basic building blocks of protein |
| polypeptide | a molecule made up of a chain of amino acids |
| genetic code | the system whereby the nucleotide triplets in DNA and RNA contain the info for synthesizing proteins from the 20 amino acids |
| codon | a triplet of nucleotide bases in mRNA that specifies an amino acid or the initiation or termination of a polypeptide sequence |
| gene | the fundamental unit of heredity; consists of a sequence of DNA bases that carries the information for synthesizing a protein or polypeptide and occupies a specific chromosomal locus |
| messenger RNA | strand of RNA synthesized in the nucleus as a complement to a specific gene (transcription)... carries the info for the sequence of amino acids to make a specific protein into the cytoplasm, where it is read at a ribosome and a protein molecule is synthesized (translation) |
| transfer RNA | RNA molecules that bind to specific amino acids and transport them to ribosomes to be used during protein synthesis |
| chromatin | the diffuse form of DNA as it exists during the interphase of the cell cycle |
| mitosis | somatic cell division in which a single cell divides to produce two identical daughter cells |
| meiosis | cell division that occurs in the testes and ovaries that leads to the formation of sperm and ova (gametes) |
| chromosomes | discrete structures composed of condensed DNA and supporting proteins |
| centromere | condensed and constricted region of a chromosome, during mitosis and meiosis, location where sister chromatids attach to one another |
| diploid number | full complement of paired chromosomes in a somatic cell; in humans, the diploid number is 46 |
| haploid number | the number of chromosomes found in a gamete, representing one from each pair found in a diploid somatic cell; in humans, the haploid number is 23 |
| homologous chromosomes | members of the same pair of chromosomes (or autosomes)... undergo crossing over during mitosis |
| alleles | alternative versions of a gene, are distinguished from one another by their differing effects on the phenotypic expression of the same gene |
| homozygous | having the same allele at the loci for a gene on both members of a pair of homologous chromosomes |
| locus | the location of a gene on a chromosome, identified by the number of the chromosome on which it is found and its position on the chromosome |
| heterozygous | having two different alleles at the loci for a gene on a pair of homologous chromosomes |
| zygote | a fertilized egg |
| crossing over | exchange of genetic material between homologous chromosomes during the first prophase of meiosis; mechanism for genetic recombination |
| recombination | the rearrangement of genes on homologous chromosomes that occurs during crossing over in meiosis, source of variation arising out of sexual reproduction; important for increasing rates of natural selection |
| karyotype | the complete chromosomal complement of an individual; usually based on a photograph of the chromosomes visualized under a microscope |
| autosomes | any of the chromosomes other than sex chromosomes |
| sex chromosomes | in mammals, chromosomes X and Y, with XX producing females and XY producing males |
| nondisjunction error | the failure of homologous chromosomes (chromatids) to split properly during cell division; when it occurs during meiosis, it may lead to the formation of gametes that are missing a chromosomes or have an extra copy of a chromosome |
| genome | the sum total of all genes carried by an individual |
| polymerase chain reaction (PCR) | method for amplifying DNA sequences using the Taq polymerase enzyme; can potentially produce millions or billions of copies of a DNA segment starting from a very small number of target DNA |
| mitochondrial DNA | small loop of NDA found in the mitochondria, clonally and maternally inherited |
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