Biology - TALONS Grade 9

DNA

deoxyribonucleic acid is a molecule made of two strands of nucleotides linked together.

RNA

ribonucleic acid

structure of DNA

phosphate, sugar, nitrogenous base.

nucleotide

found in DNA and consists of phosphate, sugar, and nitrogenous base.

nitrogenous bases

adenine, cytosine, guanine, and thymine.

complementary bases

A—T, G—C.

what does 5’ and 3’ refer to?

the numbering of the carbon atoms in the sugar component. 5’ is bonded to phosphate whilst 3’ is bonded to hydroxyl (—OH).

what is 3’-C-T-G-G-G-5’ complementary strand?

5’-G-A-C-C-C-3’

chromatin

fibres of DNA in a condensed form. the structure is curled in order to compress the DNA.

chromosome

structure composed of chromatins (condensed form of DNA).

where does the sex chromosome occur?

in the 23rd chromosome.

allele

different form of the same gene.

karyotype

photo of homologous chromosomes in a cell.

heterologous chromosomes

chromosome pairs with different gene sequences.

homologous chromosomes

chromosome pairs with similar genes from each parent that align during meiosis for genetic recombination.

chromosomal mosaicism

extra chromosomes in certain parts of their body.

trisomy

when a chromosome has three copies instead of two.

translocation

segment of another chromosome attaches itself to another chromosome.

chromosome abnormalities

deletion, duplication, inversion, substitution translocation.

deletion

segment of the chromosome is lost.

duplication

segment of chromosome is duplicated resulting in additional genetic content.

inversion

segment of chromosome is inverted causing genetic material to be reversed.

reciprocal translocation

two parts from separate chromosomes are swapped.

robertsonian translocation

one whole chromosome fuses with another at the centromere.

rings

chromosome segment breaks off and forms a ring structure. may or may not involve loss of genetic information.

substitution

one base pair in DNA sequence is replaced by another.

what is DNA replication?

process of duplicating DNA through splitting an existing strand and building a complementary strand using information on original strand.

DNA polymerase

builds from 5’ to 3’ (lagging) or 3’ to 5’ (leading). uses deoxyribonucleoside triphosphates as building blocks and energy source.

helicase

unwinds DNA double helix by breaking hydrogen bond between nucleotides.

ligase

connects okazaki fragments on lagging strand.

primase

synthesizes short RNA primer for ligase to follow.

endonucleases

makes cuts in DNA strand.

process of DNA replication

helicase, primase, DNA polymerase, ligase.

genetics

field of biology focusing on heredity.

trait

inherited characteristic.

law of segregation

if an organism is heterozygous, the alleles will split during gamete formation (Ff is now F and f for Punnett square).

dominant

allele or trait expressed regardless of other allele’s identity.

recessive

allele or trait expressed only when two alleles are present.

phenotype

physical description of trait (i.e. brown hair).

genotype

genetic combination of alleles for a trait (i.e. Bbgg for black hair and green eyes).

homozygous

organism with two of the same alleles for a particular trait.

heterozygous

organism with two different alleles for a particular trait.

punnett square

figure to represent inheritance of traits.

codominance

condition where both alleles are equally expressed (both alleles are dominant).

incomplete dominance

neither allele completely conceals the presence of the other leading to a result between a dominant and recessive phenotype.

sex-linked traits

trait controlled by genes on sex chromosomes (i.e. colour deficiencies).

law of independent assortment

alleles of two or more different genes get sorted independently from each other (hair colour does not affect eye colour).

acute intravascular hemolytic transfusion reaction

incompatibility of blood between recipient and donor. characterized by hemolysis (rapid destruction) of donor red blood cells.

mutation

permanent change in genetic material.

selective advantage

genetic advantage that improves change of survival.

natural selection

characteristics of a population change over many generations as only those who survive are able to pass down their traits to offspring.

adaptation

structural or behavioural feature or physiological process that helps survivability.

adaptive radiation

diversification of a common ancestral species into a variety of differently adapted species.

gamete

fusion of haploid cells in sexually reproducing organisms.

extinction

when a species dies out from Earth.

mutagen

substance or event that increases the rate of mutation.

carcinogen

substance or agent that causes cancer.

artificial selection

selective pressure applied by humans to improve or modify desirable traits.

monoculture

repeated planting of the same varieties of a species over large expanses of land.

recombinant DNA

DNA molecule that includes genetic material from a different source.

in vitro fertilization (IVF)

process resulting in female’s eggs being fertilized outside of the body.

gene therapy

experimental treatment to cure genetic disorders through inserting a healthy gene into disorder-affected cells of tissues.