Chapter 5 - Inheritance Flashcards
How many sets of chromosomes do sex cells have?
1 set
What is another name for sex cells?& when are they produced?
Gametes
Produced when cells in the sex organs divide by MEIOSIS
Explain how offspring produced by asexual reproduction are produced? And what do they contain?
Offspring produced by asexual reproduction are
- produced by mitosis so
- they contain all the same alleles as the parent cells
What is a gene?
A small section of DNA which controls a characteristic
Why does sexual reproduction result in variety?
- each gamete is slightly different from the rest, containg a random mixture of the original chromosome pairs because of meiosis causing variety
- also because the genetic information of both parents is combined
What is meant by mutation?
Change in the genetic composition of a cell
Describe the process of mitosis?
1 the cell copies the chromosome
2 this cell then split in two to form two disunited cells that are genetically identical
Who mainly carries out asexual reproduction?
Plants and bacteria
In mitosis, what shape do the chromosomes get copied in?
X
In mitosis, what do the 2 daughter cells look like?
Identical to the original parent cell
What is a karyotype?
The complete set of chromosomes for a species called a karyotype
Explain the process of meiosis?
1 the DNA replicates so the chromosomes double
2 the pair of chromosomes line up then separate into 2 new cells
3 the chromosomes then split again into 4 cells
What does meiosis leave you with?
Half the number of normal chromosomes - instead of 46 each egg/ sperm will have 23 unpaired chromosomes
Why do all organisms need to produce new cells?
1 growth
2 repair of damaged tissues or replacement of worn out cells
3 asexual reproduction
What is DNA
The chemical which chromosomes are made from
What is a chromosome?
Thread like structure holding genes
How is genetic information found/carried?
It is carried as genes on chromosomes
What is a karyotype?
The complete set of chromosomes for a species
Why do organisms need to produce new cells?
1 growth
2 repair of damaged tissues / replacement of worn out cells
3 asexual reproduction
In Asexual production how are new cells produced? + what do they contain?
Mitosis so that they contain all the same alleles as the parent cells (contain all the genetic information of the previous cells)
What do all new cells formed by mitosis have to contain?
All the genetic information of the previous cells
What is mitosis?+ what does it produce
The division of cells which produces 2 genetically identical daughter cells
Another name for sex cells?
Gametes
When are gametes produced?
When cells in the sex organs divide by meiosis
Where is meiosis carried out?
2
The ovaries
The testes
Why do gametes only have one set of chromosomes?
If it didn’t during fertilisation when the sperm and egg fuse together the chromosome number would double in each successive generation so it prevents rhat
Why is the use and reaserch of stem cells socially and ethically controversial?
- religious groups may feel it’s wrong
- violation of the human rights of the embryo as it can’t give permission
- they could cause cancer
- reaserch ing could be slow expensive and hard to control
Describe the structure of DNA? & what is it made up of
- A long stranded molecule
- made up of 4 chemical bases
How are proteins made specifically?
Each gene codes for a particular sequence of amino acids to make a specific protein
Describe some of the experiments carried out by Mendel using pea plants
Crossbreed different types of peas and recorded the types of offspring
How many chromosomes are there in the nucleus of a human nerve cell?
46
If the father has a genetic disorder why dosent the son neccesrily inherit it?
- inherited from mother normal allele
- the allele for the disorder is recessive
How does a chromosome become two strands?
The DNA replicates
What type of cell division produces gametes ?
Meiosis
What is a dominant allele?
An allele that is expressed if just one copy of the allele is present
What is homozygous?
2 alleles of the same type are present
What is heterozygous?
Where one allele is dominant, one is recessive
What is phenotype?
The physical characteristic of an organism determined by its genotype
What is a genotype?
The genetic makeup of an organism displaying the different alleles inherited
What is cystic fibrosis?
A disorder of cell membranes that cause various organs to be clogged by a thick sticky mucus
What is polydactyly?
An inherited disorder caused be a dominant allele
In mitosis what happens to the genetic material before the cell divides?
The genetic material is replicates
What does alleles mean?
Alternative forms of the same gene
What is meant by recessive?
An allele that is only expressed if two copies of it is inherited
Why would a child look similar to its parents?
The DNA is passed from the parens to the child in sexual reproduction
Why would a child not look identical to either of its parents?
- they might have a mutation
- the genetic information is from two parents combined
What process is when an egg and sperm join together?
Fertilisation
Why did no one recognise mendals achievements until after he died?
No one had seen chromosomes and people didn’t understand, so he died without his work being recognised
How can stem cells be used to help treat medical conditions?
It’s possible to be able tot grow whole new organs from embryonic stem cells
Examples of stem cells used to treat disease?
- infertility
- blindness
- being paralysed
- spinal injuries
What is the function of stem cells?
Stem cells differentiate to form the specialised cells of your body that make up your various tissues and organs
How does differentiation differ in plant and animal cells?
Most types of animal cell differentiate at an early stage of development
Many plant cells can differentiate throughout their lives
What are unspecialised cells?
Stem cells
Name the sources of stem cells in humans
Embryos and bone marrow
Mitosis and meiosis differencesv
Meiosis = producing gametes (egg or sperm) Mitosis= cell division
Describe the structure of DNA
Two strands coiled into a double helix (a cross shape)
In meiosis why is the halving of the chromosome number important?
Because when the sperm and egg fuse together during fertilisation the embryo produced has the normal number of 46 again
What is the main purpose of meiosis and mitosis?
Mitosis - growth
Meiosis - variation
What is an allele?
One form of a gene
What is meant by recessive?
Not expressed if a dominant allele is present
When an egg cell forms into an embryo what is this called?
Mitosis
What is meant by recessive?
Not expressed if dominant allele is present
What is genetic material made of?
DNA
Give ethical objections to embryo screening?
May lead to damage to embryo
Embryo can’t give consent
Arguments in favour of embryo screening?
Prevent having child with disorder - prevents future suffering
Embryo cells could be used in stem cell treatment
How does a chromosome become two strands?
Copies of genetic material were made
Explain why chromosomes must become two strands before the cell divides?
One copy of each chromosome to each offspring cell
Each offspring cell receives a complete set of genetic material
Name the type of cell division that produces gametes?
Meiosis
What happens to the genetic material before a cell divides?
It duplicates
Why can variety come out of sexual reproduction?
Fertilisation occurs
Leading to mixing genetic information
Meiosis causes variation
What is meant by an allele?
Alternative forms of the same gene
What is affected by cystic fibrosis?
Cell membranes
Why do you inherit characteristics?
You receive either two recessive from either parent or one dominant gene from one parent
What does a cell use a gene code for?
To use amino acids in the specific order to manufacture protein or enzymes or hormones
What does a child only inherit half characteristics from each parent?
Gametes contain onl half genetic information due to meiosis
Where is DNA found in a human cell?
In the chromosomes
In the nucleus
How do body cells divide?
By mitosis
When a body cell divides by mitosis what happens?
Copies of the genetic material are made
The cell divides once to form two genetically identical body cells
When does mitosis occur?
During growth or to produce replacement cells
Where is the genetic information contained?
The chromosomes
What do body cells contain?
Two sets of chromosomes
What do gametes contain?
Only one set of chromosomes
How do cells in reproductive organs divide?
To form gametes
When does mitosis occur?
During growth
Or to produce replacement cells
What is meiosis?
When a cell divides to form gametes
What happens during meiosis?
Copies of genetic information are made
The cell divides twice to form four gametes
Each with a single set of chromosomes
What happens when gametes join at fertilisation?
Single body cell with new pairs of chromosomes is formed
A new individual then develops by this cell repeatedly diving by mitosis
In mature animals, what is cell division restricted to?
Repair and replacement
What is the definition of a dominant allele?
An allele that controls the development of a characteristic when it is present on only one of the chromosomes
What is the definition of a recessive allele?
An allele controls the development of characteristics only if the dominant allele is not present
What are chromosomes made up of?
Large molecules of DNA
What is the structure of chromosomes?
Double helix structure
What does each gene code for?
A particular combination of amino acids which make a specific protein
What cells from humans can be made to differentiate into many different types of cells?
Human embryos
Bone marrow
Called stem cells
What conditions can stem cell be used to treat?
Paralysis
The cells of offspring produced by asexual production at produced by what?
Mitosis from the parental cells
Why does sexual reproduction give rise to variation?
When gametes dude one of each pair of alleles comes from each parent
In females what are the sex chromosomes?
The same
XX
In makes what are the sex chromosomes?
They are different
XY
In human body cells what chromosomes carries the genes that determine sex?
One of the 23 pairs of chromosomes carries the genes that determine the sex
What is polydactyly?
Having extra fingers or toes
What is polydactyly caused from?
It’s caused by a dominant allele of a gene
And can therefore be passed on by only one parent who has the disorder
What is cystic fibrosis?
A disorder of cell membranes
Describe cystic fibrosis?
Had to be inherited from both parents
Parents may be carriers of the disorder without having T the disorder themselves
Caused by a recessive allele or a gene
Why did Mendel become a monk?
To get an education
What did Mendel find from cross breeding plants?
That the characteristics were inherited in clear and predictable patterns
Why did no one recognise mendels work?
No one knew about genes or chromosomes so people didn’t understand his theories
He was a monk and didn’t carry such credibility
What are genes?
Smal sections of DNA
What does DNA carry?
The instructions to make the proteins that form most of the cell structures
These proteins include the enzymes that control cell chemistry
What is DNA made of?
A combination of four different chemical bases
These are grouped into three and each group of three codes for an amino acid
What controls the order in which amino acids are put together?
The order of the chemical bases that make up DNA
What do the order of bases control?
The order in which amino acids are put together so that they make a particular protein for use in your body cell
Each gene codes for a particular combination of amino acids which makes a specific protein
What happens if there is a change or mutation in a single group of bass?
The whole protein structure and the way it works
What does each gene code for?
A particular combination of amino acids
Which makes a specific protein
What is an exception of having unique DNA?
Having a twin
What are DNA fingerprints?
Patterns of DMA
What can DNA fingerprints be used for?
Solving crimes
Finding the biological father of a child when there is a doubt
Where is DNA found in a human cell?
In the chromosomes
In the nucleus
How do plants use the glucose they make?
Converted to starch for storage To make amino acids To make cellulose To make fat or oil for storage For active transport
Why does a person usually inherit two alleles of each gene?
One from egg
One from sperm
Properties of meiosis?
sexual Occurs in ovary or tested Half number of chromosomes (23) Variation 4 gametes produced 2 divisions
Properties of mitosis?
Asexual Occurs in cells Same number of chromosomes (46) Identical 2 cells produced 1 division
Why might a genetic prediction not be right?
Chance which two gametes fuse
Difference between alleles and genes?
Alleles = different forms of a gene controlling a characteristic Genes = pieces of DNA on chromosomes carrying information that determines the characteristic
What is homozygous? With examples.
Possessing identical alleles
BB
bb
What is heterozygous? With an example.
Carrying different alleles
Eg Bb
Each gene contains a code. What is this for?
Combine amino acids in the correct order
To make protein
What do we call inherited factors?
Genes
How are inherited factors passed from generation to generation?
Gametes in sex cells
Advantages of stem cells?
Can be grown in stem cells in a laboratory in large numbers
Can be used to treat human diseases
Disadvantages of stem cells?
Could grow out of control
Expensive
Take drugs for rest of life
Why is breathing rate and amount of oxygen used still high after exercise?
Repay oxygen debt
Break down lactic acid into water and carbon dioxide
How do plants get energy?
Light energy is trapped by chlorophyll in chloroplasts
HOW DO PLANTS USE GLUCOSE
To make starch for storage To make fats and oils for storage To make amino acids To make cellulose For active transport
How does a fertilised egg undergo cell division?
Mitosis
What is evidence something is recessive?
Skips a generation
Why is biogas pumped into a generator instead of air?
Best temperature for respiration for microorganism
Higher rate of biogas production
