SCIENCE: 2ND QUARTERLY EXAMINATION

Genes

Small units of information inside our cells that contain instructions for how our bodies develop and function.

They code for traits like our eye color, hair color, and height.

DNA

A molecule that carries genetic information in living organisms. It looks like a ladder (double helix) and is found inside the nucleus of our cells.

Stands for “deoxyribonucleic acid”

Genetic Code

A language that DNA uses to give instructions to cells.

Nucleotides

ADENINE (A)

THYMINE (T)

CYTOSINE (C)

GUANINE (G)

(A) with (T) | (G) with (C)

Amino acids

The building blocks for proteins. Our DNA codes for different proteins that perform specific functions in our body.

46 Chromosomes, 23

Humans have (beep) chromosomes, which come in pairs, with (beep) inherited from each parent.

Genetic Inheritance

The passing of traits from parents to their offspring.

Genotype

Refers to the alleles an organism has inherited for a particular gene.

Phenotype

A result of the expression of one or more genes.

Example: Brown hair, AB blood type, Blue eye color

Dominant

Only ONE allele is needed for the trait to be expressed.

Recessive

TWO alleles are needed for the trait to be expressed.

Incomplete Dominance

Both alleles are partially expressed in an phenotype.

(It will mix together)

Metacentric

The centromere is located at the center of the chromosome, forming two equal arms.

Subtemetacentric

The centromere is slightly off center, resulting in one long arm and one shorter arm.

Telocentric

The centromere is located at the end of the chromosome.

Acrocentric

The centromere is significantly off-center, resulting in one extremely short arm and one extremely long arm.

Homologous Chromosomes

They have the same location of the centromere.

They contain the sate set of genes in the same order along the entire length of their chromosomal arms.

Their chromosomal arms are of the same length.

Diploid Cells

Haploid Cells

Chromosomes

Structure Of Chromosomes

Eukaryotic Cells

Prokaryotic Cells

Chromosome Number

Prophase I

Metaphase I

Anaphase I

Telophase I and Cytokinesis

Prophase II

Metaphase II

Anaphase II

Telophase II and Cytokinesis

Meiosis

(Reduction Division)

•Only produces gametes.

•Begins with a diploid cell.

•Has two cell division stages. Meiosis I and II

Gametes

Sex cells:

Male = Sperm Cells | Female = Egg Cells

Meiosis I

Prophase I

Metaphase I

Anaphase I

Telophase I

Produces two haploid cells each containing one chromosome from the homologous pairs.

Meiosis II

Prophase II

Metaphase II

Anaphase II

Telophase II

Separates sister chromatids to produce four haploid cells.

Tetrad

Group of four sister chromatids in paired homologous chromosomes.

Alleles

Different versions of the same gene on each chromosome.

Crossing over

Also called as Recombination. Chromatids from each homologous chromosomes exchange segments of alleles.