Chapters 3 & 4: Biological Anthropology

Gregor Mendel

Father of genetics; studied pea plants; demonstrated principles of inheritance (dominance, segregation, independent assortment).

Monohybrid Cross

Mendel’s experiment with one trait; F1 all yellow seeds, F2 showed reappearance of recessive trait.

Particulate Inheritance

Traits are controlled by discrete units (genes) inherited from each parent; remain unchanged.

Dominance

When two alleles are present, the dominant is expressed while the recessive is masked.

Law of Segregation

Allele pairs separate randomly during gamete formation; each gamete receives one allele.

Law of Independent Assortment

Alleles for different traits assort independently during gamete formation.

Phenotype

Physical trait expression.

Genotype

Genetic makeup underlying traits.

Homozygous

Two identical alleles for a trait.

Heterozygous

Two different alleles for a trait.

DNA (Deoxyribonucleic Acid)

Molecule storing genetic info; double helix of nucleotides.

Nuclear DNA

DNA in chromosomes, housed in the nucleus; inherited from both parents.

Mitochondrial DNA (mtDNA)

Circular DNA in mitochondria; inherited only from the mother.

Chromosome

Tightly wound DNA visible during cell division. Humans have 46 (23 pairs).

Karyotype

The complete set of an individual’s chromosomes.

Autosomes

Chromosome pairs 1–22 (non-sex).

Sex Chromosomes

23rd pair (XX = female, XY = male).

Homologous Chromosomes

One chromosome from each parent; same loci, may carry different alleles.

Somatic Cells

Body cells; diploid (46 chromosomes).

Gametes

Sex cells, Eggs or sperm; haploid (23 chromosomes).

Zygote

Fertilized egg (diploid 46 chromosomes).

Mitosis

Cell division in somatic cells; produces 2 identical diploid cells.

Meiosis

Cell division in gametes; produces 4 genetically unique haploid cells. Increases genetic variation.

Nucelotides

DNA subunits; made of sugar, phosphate, and a nitrogenous base.

Purines

Compound bases for DNA with two rings (Adenine, Guanine).

Pyrimidines

Compound bases for DNA with one ring (Thymine, Cytosine)

Base Pairing

A pairs with T; G pairs with C.

Rosalind Franklin

Produced X-ray diffraction images of DNA; evidence for double helix.

DNA Replication

Before cell division, DNA unzips and makes identical copies using base-pairing rules.

Protein Synthesis

Process of translating genotype into phenotype via proteins.

Transcription

DNA → mRNA inside the nucleus.

Translation

mRNA → protein at ribosomes; tRNA brings amino acids.

Codon

Sequence of 3 nucleotides in mRNA that codes for an amino acid.

Redundancy of Code

Multiple codons can code for the same amino acid.

Genome

Complete genetic material of an organism.

Exons

Coding DNA regions that get expressed as proteins.

Introns

Non-coding regions removed before translation.

Mutation

Any alteration in DNA; source of new variation.

Point Mutation

Change in a single base

Duplication

Repeating a DNA segment

Deletion (Frameshift)

Loss of bases that shifts the reading frame

Silent Mutation

No effect on protein produced

Beneficial Mutation

Confers a selective advantage

Mendelian Inheritance

Single-gene traits with dominant/recessive alleles.

Codominance

Both alleles expressed equally in heterozygotes (e.g., AB blood type).

Polygenic Traits

Traits influenced by multiple genes; show continuous variation (e.g., height).

Pleiotropy

One gene influences multiple traits

Structural Genes

Codes for proteins

Regulatory Genes

Control when/where other genes are expressed

Homeotic Genes

Guide body plan and structure during development.

RNA

single stranded molecule formed with ribose sugar (instead of deoxyribose), key in the transcription process of protein synthesis

Locus

location of a gene on a chromosome

Diploid

two complete sets of chromosomes, with one set inherited from each parent

Haploid

a cell that contains a single set of chromosomes

Adenine

= Thymine (base pairing)

Guanine

= Cytosine (base pairing)

Transfer RNA (tRNA)

molecules bind to the complementary mRNA strand at the ribosome, bringing with them amino acids specified by the mRNA codon

Structural Genes

code for the sequence of a known polypeptide change

transcriptome

all of the mRNAs encoded by the genome

Proteome

all of the proteins encoded by the genome/transcriptome