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