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Biology > Inheritance > Flashcards

Inheritance Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How many chromosomes do human cells have

A

23 pairs

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2
Q

How many chromosomes do human gametes have

A

23 single chromosomes

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3
Q

How are gametes made

A

By meiosis

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4
Q

What process makes non identical cells

A

Meiosis

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5
Q

What us sexual reproduction

A

The fusion of male and female gametes

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6
Q

What is sexual reproduction in plants

A

The fusion of pollen and egg cells in flowering plants

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7
Q

Why is there variation in sexual reproduction

A

There is mixing of genetic information

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8
Q

What is asexual reproduction

A

There is only one parent
There is no fusion of gametes
There is no mixing of genetic information and the offspring are genetically identical
It only involves mitosis

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9
Q

Describe the process of meiosis

A

In the first stage, all the chromosomes are copied
The cell divides twice to form four gametes, each with a single set of chromosomes
All gametes are genetically different from each other

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10
Q

Explain how fertilisation restores the full number of chromosomes

A

Gametes join at fertilisation to restore the normal number of chromosomes
The new cell divides by mitosis producing a clump of identical cells
This is embryo
As the embryo develops the cells differentiate forming different cell types

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11
Q

Advantages of sexual reproduction

A

Produces variation in the offspring
If the environment changes variation gives a survival advantage by natural selection
Natural selection can be speeded up by humans in selective breeding to increase food production

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12
Q

Advantages of asexual reproduction

A

Only one parent needed
More time and energy efficient as do not need to find a mate
Faster than sexual reproduction
Many identical offspring can be produced when conditions are favorable

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13
Q

Describe how malarial parasites reproduce

A

Malarial parasites reproduce asexually in the human host, but sexually in the mosquito

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14
Q

Describe how fungi reproduce

A

Many fungi reproduce asexually by spores but also reproduce sexually to give variation

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15
Q

Describe how plants reproduce

A

Many plants produce seeds sexually, but also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils

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16
Q

Describe the structure of DNA

A

DNA is a polymer made up of two strands forming a double helix.
The DNA is contained in structures called chromosomes

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17
Q

What’s a gene

A

A gene is a small section of DNA on a chromosome
Each gene codes for a particular sequence of amino acids, to make a specific protein

18
Q

What’s a genome

A

The genome of an organism is the entire genetic material of that organism
The whole human genome has now been studied and this will have great importance for medicine in the future

19
Q

What is the importance of understanding the human genome

A

It will help us to search for genes that are linked to different types of diseases
It will help us to understand and treat inherited disorders
It can be used to trace human migration patterns from the past

20
Q

Describe the structure of DNA (triple)

A

DNA is a polymer made from four different nucleotides
Each nucleotide consists of a phosphate group, sugar molecule, and a base
The phosphate group and the sugar molecule never change
There are 4 different bases: A,C,G,T

21
Q

Which bases bind to eachother

A

A binds with T
G binds with C

22
Q

How do amino acids affect a protein

A

The order of amino acids in the protein determines its shape and its function

23
Q

How is the order of amino acids in a protein determined

A

By the sequence of bases in the gene for that protein

24
Q

Describe the process of protein synthesis

A

The first stage is transcription, this takes place in the nucleus
In this stage, the base sequence of the gene is copied into a complementary template molecule
This template is called mRNA
The mRNA now passes out of the nucleus and into the cytoplasm
The second stage is called translation
In this stage, the mRNA molecule attaches to a ribosome
Amino acids are now brought to the ribosome by tRNA
The ribosome now reads the triplets of bases on the mRNA and uses this to join together the correct amino acids in the correct order
Once the protein chain is complete it folds into its unique shape which enables it to do its job

25
Q

What is the code for a particular amino acid

A

A sequence of three bases

26
Q

What is a mutation

A

A change to a base
They happen all the time
Most do not change the protein, or only change it slightly so that its appearance or function is not changed

27
Q

What happens if a mutation codes for an altered protein

A

This changes the shape of the protein
An enzyme may no longer fit the substrate binding site as the active site of an enzyme may change shape
In a structural protein it may lose its strength

28
Q

What do non-coding parts of DNA do

A

They can switch genes on and off which tells genes when to produce proteins
Mutations in these regions may cause a protein to be produced that is not meant to have at that time
This could have a very significant effect on the cell

29
Q

What are alleles

A

Versions of a gene

30
Q

What is a genotype

A

The genotype of a person tells us the allele is present eg:Ee

31
Q

What are homozygous alleles

A

When you have two copies of the same allele eg: EE

32
Q

What is the phenotype of a person

A

It tells us the characteristics caused by the person’s alleles eg: wet ear wax

33
Q

Heterozygous alleles meaning

A

Two different alleles
Eg: Ee

34
Q

What’s a dominant allele

A

It will show in the phenotype even if there is only one copy present

35
Q

What’s a recessive allele

A

Will only show in the phenotype if two copies are present
Eg: ee

36
Q

What is cystic fibrosis

A

It’s a disorder of cell membranes
Cystic fibrosis is controlled by a single gene that has two alleles
In order to have cystic fibrosis the person has to have two copies of the recessive allele
A person with one dominant allele and one recessive does not have cystic fibrosis but they are a carrier

37
Q

What is polydactyly

A

When people have extra fingers or toes
Polydactyly is caused by a dominant allele
This means if someone has one copy of the dominant allele then they have polydactyly
You cannot be a carrier of polydactyly as it has a dominant allele

38
Q

What is embryo screening

A

Embryos are tested to see if they have the alleles for inherited disorders
Embryos which do not have the defective alleles are implanted into the woman
These can then develop into healthy offspring

39
Q

Problems with embryo screening

A

Embryo screening is expensive.
Some people think that the money should be spent elsewhere in the Health Service.
Often a large number of embryos are created but only a small number are implanted. That means that some healthy embryos are destroyed and some people think that that is unethical.
In the future we may be able to screen embryos to produce offspring with desirable features eg taller or more intelligent offspring. Many people find this unethical.

40
Q

What is gene therapy

A

In the future, scientists may be able to correct faulty alleles and use this to treat inherited disorders
This is still experimental

41
Q

What are males sex chromosomes

A

XY

42
Q

What are females sex chromosomes

A

XX

Biology (10 decks)

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