Genes, Inheritance, and Selection (OCR)

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57 Terms

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Gamete

These are reproductive cells, like sperm or egg cells, that carry half the genetic information (one set of chromosomes) an organism has.

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Autosomes

Chromosomes that are not involved in determining sex.

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Sex Chromosomes

Chromosomes that determine the sex of an individual.

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Functions of Gene

  1. Protein Coding

  2. Non-coding RNA

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Transcription

The process by which the information in a sequence of DNA nucleotides is copied to a newly synthesised messenger RNA (mRNA) strand.

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Allele

One of two or more versions of a genetic sequence at a particular region on a chromosome.

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Variant

Describes a subtype of a microorganism that is genetically distinct from a main strain, but not sufficiently different to be termed a distinct strain.

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Complete Dominance

The dominant allele's phenotype completely masks the recessive allele's effect in heterozygous individuals.

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Incomplete Dominance

The phenotype of heterozygous individuals is a blend of both alleles.

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Dominant

An allele is dominant if it expresses its phenotype even when only one copy is present in the genotype.

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Recessive

An allele is recessive if it expresses its phenotype only when two copies of the allele are present in the genotype.

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Homozygous

An individual is homozygous for a trait if they have two identical alleles for that trait.

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Heterozygous

An individual is heterozygous for a trait if they have two different alleles for that trait.

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Genotype

The genetic makeup of an organism.

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Phenotype

The observable characteristics of an organism, influenced by the genotype and environmental factors.

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Genome

The complete set of DNA (deoxyribonucleic acid) in an organism, including all of its genes and non-coding sequences.

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Human Genome Size

Approximately 3 billion base pairs.

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Human Gene Count

About 20,000-25,000 genes.

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Human Chromosomes Pairs

Humans have 23 pairs of chromosomes (46 total), including 22 pairs of autosomes (non sex-related chromosomes) and 1 pair of sex chromosomes (XX or XY).

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Epigenetics

Study of changes in gene expression caused by mechanisms other than changes in the DNA sequence.

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Discontinuous Variation

Traits with a limited number of distinct phenotypes.

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Continuous Variation

Traits that exhibit a range of phenotypes.

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Mutations

Changes in the DNA sequence that can occur spontaneously or due to environmental factors.

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Point Mutations

Are single nucleotide changes.

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Insertions/Deletions

Addition or loss of nucleotide segments.

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Copy Number Variations

Duplications or deletions of large DNA segments.

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Neutral Mutations

Most mutations have no effect on the phenotype.

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Beneficial Mutations

Rare mutations that confer an advantage in the organism’s environment.

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Harmful Mutations

Mutations that cause diseases or disorders.

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Silent Mutations

Do not affect protein function and thus have no impact on phenotype.

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Missense Mutations

Change one amino acid in a protein, which can alter its function.

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Nonsense Mutations

Introduction of a premature stop codon leading to a truncated, usually nonfunctional protein.

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Asexual Reproduction

The production of offspring by a single organism without the fusion of gametes.

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Sexual Reproduction

The production of new organisms by the combination of genetic information of two individuals of different sexes.

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Haploid

Cells containing a single (n) set of chromosomes.

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Diploid

Cells containing two (2n) sets of chromosomes, one from each parent.

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Punnett Squares

A tool used to predict the outcome of genetic crosses.

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Monohybrid Cross

Involves one gene with two alleles.

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Polygenic Inheritance

Traits that are controlled by multiple genes, each contributing to the phenotype.

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Law of Segregation

Explains that each individual has two alleles for each gene, which segregate during gamete formation, so each gamete receives one allele.

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Law of Independent Assortment

Explains that genes for different traits assort independently of one another during gamete formation.

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Genetic Variation

Refers to the differences in DNA sequences between individuals of the same species.

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Natural Classification Systems

Aims to group organisms based on their evolutionary relationships, reflecting their shared ancestry.

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Microscopy

The invention of powerful microscopes allowed scientists to observe and categorize organisms based on cellular structures, leading to the identification of microorganisms and a deeper understanding of cell types.

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Paleontology

The study of fossils provided insights into extinct organisms and their relationships to living species, refining the evolutionary picture.

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Evolution

A change in the inherited characteristics of a population over time, through a process of natural selection, may result in the formation of new species.

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Fossil Record

Fossils are the preserved remains or traces of organisms from past eras as they offer a glimpse into the history of life and provide a timeline for how life has changed over time.

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Transitional Fossils

Fossils that exhibit characteristics of both ancestral and descendant species.

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Fossil Distribution

The distribution of fossils across different geographic locations reflects the movement and diversification of life forms over time.

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Antibiotic Resistance in Bacteria

Bacteria reproduce rapidly, and mutations in their DNA can occur during this process. Some mutations can provide bacteria with resistance to antibiotics, a phenomenon known as antibiotic resistance.

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Antibiotic Use as a Selective Pressure

It is when antibiotics are used, they kill bacteria that are susceptible to them.

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Increased Prevalence of Resistant Bacteria

Over time, the use of antibiotics selects resistant strains of bacteria, leading to an increase in their prevalence.

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Vestigial Structures

When some organisms contain anatomical features that no longer have a purpose in the modern organism but may have had a function in an ancestral organism.

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Molecular Evidence

Comparing DNA sequences from different organisms can provide evidence of evolution.

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Voyage of the Beagle

A work by Charles Darwin where he observed distinct variations among species, particularly the finches on the Galapagos, which sparked his curiosity about the origin of these variations.

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Independent Discovery

A work by Alfred Russel Wallace where he independently developed a similar theory of evolution by natural selection while working as a naturalists in Southeast Asia.

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Seedbanks

Function like a safety net, safeguarding the genetic diversity of our planet's flora in the face of potential threats.