Genetics and Cell Biology Review

Vocabulary flashcards covering key genetics and cell-biology terms from the lecture notes.

Heterozygous

Having two different alleles for a particular gene (e.g., Aa), often producing a 3:1 phenotypic ratio when crossed with another heterozygote.

3:1 Phenotypic Ratio

Typical offspring ratio from a monohybrid cross of two heterozygous parents, indicating simple dominance.

Albino Phenotype

Lack of pigmentation caused by being homozygous recessive (aa); appears in 25 % of offspring from two heterozygous (Aa) parents.

Contact Inhibition

The property of normal cells to stop dividing when crowded; cancer cells lose this ability and continue dividing.

Barr Body

An inactivated X chromosome visible in interphase nuclei; number of Barr bodies = total X chromosomes – 1 (e.g., three Barr bodies imply four X chromosomes).

Punnett Square

Predictive diagram where outer symbols represent parental gametes and inner boxes show possible progeny genotypes.

X-Linked Inheritance

Pattern in which a gene is located on the X chromosome, illustrated by Morgan’s white-eyed male fruit flies.

ww Genotype

Homozygous recessive condition that produces non-wooly hair in the noted example.

Complementary Base Pairing

In DNA, adenine pairs with thymine and guanine pairs with cytosine, holding the double helix together.

DNA Polymerase

Main enzyme that replicates DNA by adding nucleotides to a growing strand using a template.

Metaphase

Mitotic stage in which duplicated chromosomes line up at the cell’s equatorial plane before separation.

Binary Fission

Asexual reproduction in bacteria during which duplicated origins of replication move apart before cell division.

Origin of Replication

Specific DNA sequence where replication begins; duplicates and migrates apart in prokaryotic binary fission.

Mendel’s Particulate Hypothesis

The idea that parents pass on discrete heritable units (genes) that retain their identity in offspring.

Blending Inheritance Hypothesis

Obsolete theory proposing parental genetic material mixes irreversibly in offspring, losing individual identity.

Sex Chromosomes (X and Y)

Human chromosomes that carry genes determining biological sex and various other traits.

Gene Expression in Cell Types

Different cell types use many genes; the notion that only one gene operates per cell type is incorrect.