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Biology > SB3- Genetics > Flashcards

SB3- Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What reproduction do do invertebrates do

A

Asexual reproduction is more common eg aphids produce offspring from cells formed in mitosis

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2
Q

How to plants usually reproduce

A

Asexually

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3
Q

What does sexual reproduction do

A

Combines characteristics from both parents and so produces offspring different from eachother

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4
Q

Why are different characteristics an advantage

A

If the environment changes, variation means that there is a greater chance that some offspring will be better suited to new conditions and so will me more likely to survive and reproduce

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5
Q

Why is asexual reproduction faster

A

There is no need to find a mate

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6
Q

What’s a zygote

A

When 2 gametes fuse during fertilisation

The zygote forms a ball of cells using a type of cell division called mitosis

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7
Q

What is DNA

A

It’s instructions for an organism found as code in a molecule called DNA

THE DNA of an organism is its genome

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8
Q

What’s the human genome like

A

46 very long molecules of DNA and each molecule is inside a chromosome

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9
Q

What are genes

A

Along the length of a DNA molecule are sections that each contain a code for making protein

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10
Q

How are proteins made

A

They are polymers made by linking different amino acids together in a chain

The order of amino acids is controlled by the gene

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11
Q

What kind of cell does mitosis produce

A

Diploid cells

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12
Q

What process is used to produce gametes

A

Meiosis

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13
Q

Tell me about meiosis

A

Each chromosome replicates, the 2 copies remain making each chromosome look like an X, the 2 sets of chromosomes pair up forming 23 pairs then seperate into 2 new cells, next the 2 copies of a chromosome in each x shape split into 2 more new cells therefore produces 4 haploid daughter cells

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14
Q

How does meiosis create genetic variation

A

Each chromosome in each pair contains different versions of the same genes so they are genetically
Different chromosomes so explains why brothers and sister look similar but not identical

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15
Q

Tell me the order of meiosis

A 
Interphase 
Prophase
Anaphase
Telophase
Interphase
Metaphase
Anaphase
Telophase
Cytokinesis
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16
Q

Where is DNA stored

A

In the nuclei of a cell - each molecule of DNA is tightly coiled and packaged up with proteins to from chromosomes

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17
Q

What shape is DNA

A

A double helix

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18
Q

What are the 4 bases of DNA

A

Adenine, thymine, cytosine and guanine

Make them simple often call them A, T, C and G

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19
Q

How are the bases arranged

A

In complementary base pairs

A and T always pair

C and G always pair

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20
Q

What’s a nucleotide

A

Each base is attached to a super and each sugar is attached to a phosphate group

The sugars and phosphate groups form the backbone of the DNA strands

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21
Q

How are bases joined together

A

Hydrogen bonds

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22
Q

How many bonds are between the bases

A

Cytosine and guanine form 3 hydrogen bonds between them

Thymine and adenine only form 2 bonds

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23
Q

What makes our DNA different

A

The order of the bases

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24
Q

What did Erwin Chargaff

A

He did chromatography experiments which showed the amount of A and T in an organisms DNA were the same, as were the amount of G AND C

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25
Q

What did Rosalind Franklin do

A

Took an X-ray photograph suggesting that DNA was a helix

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26
Q

What did Jerry Donohue do

A

Who showed them how DNA based could form hydrogen bonds

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27
Q

What’s the genetic code

A

How the order of the DNA bases caused amino acids to be joined in a certain order on a protein

28
Q

What’s transcription

A

DNA bases are used to make a strand of RNA (ribonucleic acid)

An enzyme called RNA POLYMERASE attached up the DNA IN front of a gene in a non-coding region (so called because it does not contain code for a protein) the enzyme separates the 2 DNA strands.

The enzyme then moves along one DNA strand (the TEMPLATE strand) adding complementary RNA nucleotides. These contain the same bases as DNA except uracil (U) is used instead of thymine (T) the nucleotides link link to form a strand of RNA (mRNA)

29
Q

What’s translation

A

The mRNA strands travel out of the nucleus through nuclear pores, in the cytoplasm the mRNA strands attach to ribosomes

A ribosome moves along the an mRNA strand three bases at a time (a codon) at each mRNA codon a molecule of transfer RNA (tRNA) with complementary bases line up- each tRNA molecule carries a specific amino acid, as the ribosomes moves along, it joins the amino acids from the tRNA molecules together, forming a polypeptide

30
Q

What happens after translation

A

The polypeptide chain folds up to form a protein with a specific shape. Some proteins contain more that one polypeptide chain

31
Q

What creates a mutation

A

A change In bases of a gene creates a genetic variant or mutation

32
Q

How can a mutation be caused

A

When DNA is not copied properly in cell division. Environmental factors can also cause mutations

Some mutations change an organisms phenotype (visible characteristics)

33
Q

What are alleles - what do they mean

A

Mutations are the reason alleles exist - one gene can have many alleles, caused by different mutations. Your characteristics are shaped by the alleles you Inherit

34
Q

What’s haemoglobin like

A

It can 4 polypeptides of two kinds a and b (in those funny Greek letters) the polypeptides fold and join up to form a globular protein which carried oxygen.

35
Q

What are mutations in non coding DNA like

A

RNA polymerase attaches to DNA bases in front of a gene, a mutation in this non-coding region may result in RNA polymerase not binding well - reducing transcription
Other non coding mutations can result In RNA polymerase binding better and producing more mRNA

36
Q

What are the 3 laws of inheritance according to Mendel

A

1) each gamete receives only one factor for a characteristic
2) the version of a factor that a gamete receives is random and does not depend on the other factors in the gamete
3) some versions of a factor are more powerful than others and always have an effect In the offspring

37
Q

Why was mendels work largely ignored

A

Did not see how ‘factors’ could explain the many variations in characteristics such as human eye colour - couldn’t see mendels ideas could explain evolution

Argued that if the factors could boy change then a species would not evolve

38
Q

What are alleles

A

Genes for the same characteristics but contain slightly different instructions that create variations eg brown and blue eyes

39
Q

How is their genetic variation

A

There are 2 copies of every gene in each body cell - each copy of a gene may be a different allele, the different combinations of Alleles in different people gives us slightly different characteristics

40
Q

What’s homozygous

A

If both alleles for one gene are the same

41
Q

What’s heterozygous

A

if the alleles are different

42
Q

What is dominat

A

It is the allele that has an effect

43
Q

What’s recessive

A

When an allele is in the genotype but not the phenotype

44
Q

When is a recessive gene seen In phenotype

A

If both alleles are recessive, the recessive characteristics are seen

45
Q

How is a dominant allele shown

A

With a capital letter

Recessive with a lower case

The dominant allele letter is always written before the recessive one

The alleles in an organism are its genotype

What the organism looks like is its phenotype

46
Q

What do we use to explain the inheritance of one gene (monohybrid inheritance)

A

Diagrams, they predict the ratios of the phenotype

47
Q

What are the sex chromosomes

A

They determined your sex

Two types: X AND Y makes a male

X and X makes a female

48
Q

What chromosomes do gametes contain

A

Egg cells all contain X sex chromosomes and Sperms contain either X or Y

49
Q

What are Punnett squares used for

A

They can demonstrate inheritance, they show possible genotypes

They calculate the theoretical probability of offspring inheriting certain genotypes / used to calculate probabilities of different phenotypes caused by alleles

Probabilities can be shown as a decimal or percentage

50
Q

What does a family pedigree chart show

A

Shows how genotypes and their resulting phenotypes are inherited in families

51
Q

What will happen if someone is given the wrong blood

A

The red blood cells in it will clump together which can kill

52
Q

How do we classify blood

A

ABO blood group system

In this system everyone’s blood is one of 4 groups: A, B, AB, O

53
Q

How is your blood group determined

A

By wether you have certain marker molecules on the outside of your red blood cells

Three main types A, B and O

54
Q

Tell me s let the genes in the ABO system

A

The gene that is responsible for the markers in the ABO system has 3 alleles, written as I (with a little letter (A,B, or O) above small like a power would be

Everyone has 2 copies of the gene so may be homozygous for Any of the 3 alleles or heterozygous for any 2 of the three alleles I(with an O) is recessive to both I^A and I^B. However a person with genotype I^a I^b shows the effect of both alleles and has the blood group AB

55
Q

What is codominance

A

When both alleles for a gene affect the phenotype eg blood group AB

56
Q

What are sex linked genetic disorders

A

The Y chromosomes are missing some of genes in X chromosomes, so a man may only have 1 allele for some genes on the X chromosome, if the allele for one of these X chromosomes genes causes genetic disorder, then a man will develop that disorder

Whereas if a women has a recessive allele for a disorder she won’t get it as she still has a healthy allele with will be dominant

So probability of a man developing it will be more than a women

57
Q

Tell me some examples of a sex linked disorder

A

Red-green colour blindness - 8% men have it only 0.5% of women have jt

A mother can be a carrier for the disorder which means she has one faulty allele and one normal allele

58
Q

What is a mutation

A

A change in a gene that creates a new allele, often occur during cell division

Happen Becuase there is a mistake in copying DNA during cell division
More likely if there is damage to the DNA caused by radiation or certain substances

Many mutations will not change a protein at all and so have no effect on phenotype

59
Q

What can mapping a persons genome do

A

Indicate their risk of developing diseases caused by different alleles of genes, also help identify best medicines to treat a persons illness

Becuase alleles we have can affect how medicines work in the body

60
Q

How is genetic variation caused

A

By the different alleles inherited during sexual reproduction

Different alleles are produced by mutations, some of which cause changes in the phenotype

61
Q

What’s environmental variation

A

Many characteristics also show environmental variation Becuase they are affected by their surroundings

Eg a plant grows according to how much light, water and nutrients it gets

62
Q

What are acquired characteristics

A

Characteristics that are changed by the environment during the life of the individual eg loss of limb

63
Q

What’s discontinuous variation

A

Is where the data can only take a limited set of values eg number of whole leaves a plant has

64
Q

What’s continuous variation

A

Where data can be any value in any range eg the leaf length in a plant

65
Q

What does a bar chart look like for discontinuous variation

A

The bars have gaps, you can only have whole numbers

66
Q

What’s a bar chart like for continuous data

A

There are no gaps with bars

Values are grouped to make it easier to see patterns In data

67
Q

What’s normal distribution for variation

A

Often forms a bell shaped curve (goes up and then down)

Called normal distribution Becuase it’s what’s expected for a large amount of data for a characteristic where:
The most common value is the middle value in the whole range
The further a value is from the median, the fewer individuals have that value

Biology (12 decks)

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