Biology - 4BI1 PearsonEdexcel

Inheritance

Gbogbo ọrọ náà

You share about 99.9% of your DNA with every other human on the planet, yet no two people (apart from identical twins) are genetically the same. The tiny differences in that remaining 0.1% account for everything from eye colour and blood group to your risk of certain diseases. Understanding how traits pass from parent to offspring - and how populations change over time - is one of the most powerful ideas in biology.

This lesson takes you from the structure of DNA through to Darwin's theory of evolution. You will learn how genes code for proteins, how alleles produce variation, how to predict the outcome of genetic crosses using Punnett squares, and why antibiotic resistance is a modern example of natural selection in action.

Ebumnobi

Understand that the genome is the entire DNA of an organism and that a gene is a section of a molecule of DNA that codes for a specific protein
Understand that the nucleus of a cell contains chromosomes on which genes are located
Describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G)
Understand that an RNA molecule is single stranded and contains uracil (U) instead of thymine (T)
Describe the stages of protein synthesis including transcription and translation, including the role of mRNA, ribosomes, tRNA, codons and anticodons
Understand how genes exist in alternative forms called alleles which give rise to differences in inherited characteristics
Understand the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, and genotype
Understand the meaning of the term codominance
Understand that most phenotypic features are the result of polygenic inheritance rather than single genes
Describe patterns of monohybrid inheritance using a genetic diagram
Understand how to interpret family pedigrees
Predict probabilities of outcomes from monohybrid crosses
Understand how the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male
Describe the determination of the sex of offspring at fertilisation, using a genetic diagram
Understand how division of a diploid cell by mitosis produces two cells that contain identical sets of chromosomes
Understand that mitosis occurs during growth, repair, cloning and asexual reproduction
Understand how division of a cell by meiosis produces four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes
Understand how random fertilisation produces genetic variation of offspring
Know that in human cells the diploid number of chromosomes is 46 and the haploid number is 23
Understand that variation within a species can be genetic, environmental, or a combination of both
Understand that mutation is a rare, random change in genetic material that can be inherited
Understand how a change in DNA can affect the phenotype by altering the sequence of amino acids in a protein
Understand how most genetic mutations have no effect on the phenotype, some have a small effect and rarely do they have a significant effect
Understand that the incidence of mutations can be increased by exposure to ionising radiation and some chemical mutagens
Explain Darwin's theory of evolution by natural selection
Understand how resistance to antibiotics can increase in bacterial populations, and appreciate how such an increase can lead to infections being difficult to control

Akọmọ Ojú-ẹkọ

In 2003, scientists completed a thirteen-year effort to sequence every gene in the human genome. The result was a blueprint of roughly 20 000 genes, each one a set of instructions for building a specific protein. From the haemoglobin that carries oxygen in your blood to the collagen that holds your skin together, proteins run the body - and genes are the recipes that make them. This lesson traces the path from DNA to protein to inherited trait, and then zooms out to see how inheritance drives evolution.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Inheritance. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

What is the complementary DNA base pair for cytosine? A) Adenine B) Thymine C) Guanine D) Uracil Answer: C
How many chromosomes are found in a human gamete? A) 46 B) 23 C) 44 D) 92 Answer: B
Which type of cell division produces genetically identical cells? A) Meiosis B) Mitosis C) Binary fission D) Fertilisation Answer: B
Two heterozygous parents (Bb) are crossed. What proportion of offspring are expected to show the recessive phenotype? A) 0% B) 25% C) 50% D) 75% Answer: B
Which of the following can increase the rate of mutation? A) A balanced diet B) Regular exercise C) Exposure to ultraviolet radiation D) Drinking water Answer: C