Bio 110 Exam 2

chapters 19-21

Somatic cell

Cells in the body except eggs and sperm, containing 46 chromosomes with homologous pairs from each parent.

Sex cell

Gametes (eggs or sperm) with 23 chromosomes, haploid and formed by meiosis.

diploid

cell with two of each chromosome, sex cells.

haploid

one member of each homologous pair of chromosomes, formed by meiosis.

Chromosome structure

Tightly coiled DNA molecule with histone proteins, located in the nucleus.

Duplicated chromosome

Consists of two sister chromatids joined at the centromere.

Homologous pairs

Corresponding chromosomes from each parent, one from the mother and one from the father.

Sister chromatid

Two genetically identical chromatids joined at the centromere.

Autosome vs sex chromosomes

Sex chromosomes determine sex, while autosomes express inherited characteristics.

Gene

Specific DNA segment for protein synthesis, located on locus.

Chromatin vs chromosomes

Chromosomes are condensed structures visible during cell division, while chromatin is extended and not visible.

Cell cycle steps

Interphase (G1, S, G2) and cell division (mitosis, cytokinesis) resulting in two daughter cells.

Interphase events

G1 (growth), S (DNA replication), G2 (preparation for mitosis); S phase is crucial for DNA replication.

Mitosis phases

Prophase (chromatin condenses), Metaphase (chromosomes align), Anaphase (chromosomes separate), Telophase (nuclear envelope forms).

Cytokinesis

Division of cytoplasm into two daughter cells, forming new nuclei.

Diploid vs haploid

Diploid has two sets of chromosomes, while haploid has one set.

Meiosis

Process in sex cells for producing haploid gametes, involving two phases for genetic diversity.

Crossing over

Occurs in meiosis prophase 1, increasing genetic diversity and ability to adapt in changing environment.

independent assortment

occurs during metaphase 1, random alignment of chromosome pairs and random distribution of entire chromosomes.

Nondisjunction

Failure of chromosome separation in meiosis, leading to abnormal chromosome numbers.

Trisomy

3 representatives of a chromosome in a cell rather than the usual 2.

Oogenesis vs spermatogenesis

Oogenesis produces one egg, while spermatogenesis produces four sperm cells.

Gene

DNA segment coding for a protein, located on chromosomes within nucleus.

Allele

Different versions of a gene, determining traits.

Male vs female chromosomes

Males have XY, females have XX chromosomes.

Sex-linked traits

Traits influenced by sex chromosomes, e.g., color blindness.

Pedigree

Displays genetic relationships in a family.

Polygenic inheritance

Trait variation influenced by multiple genes, e.g., skin color.

Pleiotropy

One gene affecting multiple traits, e.g., sickle-cell anemia.

Incomplete dominance

Heterozygote trait expression between dominant and recessive alleles.

Codominance

Both dominant alleles' effects visible in heterozygotes, e.g., blood type AB.

DNA double helix

Twisted double-stranded molecule with nucleotide units.

Nitrogenous bases

Adenine, Guanine, Thymine, Cytosine, complementary pairs A-T, C-G.

Hydrogen bonds

located in between the nitrogenous bases, holds each pair of bases together.

RNA structure

Single-stranded with uracil, ribose sugar.

Protein synthesis

Essential for cell function, directed by mRNA.

Transcription

Process in the nucleus to produce mRNA.

Translation

Process in the cytoplasm to synthesize proteins.

Intron vs Exon

Intron is non-coding, exon is coding and functional.

mRNA function

Carries DNA’s instructions for synthesizing protein from nucleus to the cytoplasm.

ribosome

mRNA and tRNA meet

Codon vs Anticodon

codon-mRNA, anticodon-tRNA

Recombinant DNA

DNA from multiple sources, created by inserting a gene of interest into another DNA piece.

Restriction enzymes

Cut DNA at specific sites, used in genetic engineering.